DE69333977T2 - Transmission with multiple resolutions as well as error-correcting coding, with multicarrier signals - Google Patents

Abstract

At the transmitter side, carrier waves are modulated according to an input signal for producing relevant signal points in a signal space diagram. The input signal is divided into, two, first and second, data streams. The signal points are divided into signal point groups to which data of the first data stream are assigned. Also, data of the second data stream are assigned to the signal points of each signal point group. A difference in the transmission error rate between first and second data streams is developed by shifting the signal points to other positions in the space diagram. At the receiver side, the first and/or second data streams can be reconstructed from a received signal. In TV broadcast service, a TV signal is divided by a transmitter into, low and high, frequency band components which are designated as a first and a second data stream respectively. Upon receiving the TV signal, a receiver can reproduce only the low frequency band component or both the low and high frequency band components, depending on its capability.

Description

The The present invention relates to a communication system for transmission Receiving a digital signal by modulating its vehicle shaft and demodulation of its carrier wave.

digital Communication systems are used in various fields Service. In particular, digital video signal transmission techniques are noticeable been improved.

Under There is a digital signal transmission method. So far are such digital signal transmission systems especially in use at e.g. a transmission between remote stations. They will be up soon a terrestrial and / or satellite television service in each Country of the world used.

The Television broadcasting systems including high-definition television, PC music, FAX and other information services are now in demand desired Data according to quantity and quality to increase, to satisfy millions of demanding viewers. Especially have to the data is increased in a given sand width of the frequency which is assigned to the television service. The data to be transferred is always ample and supplied as much as with the at the time modern techniques can be processed. It is ideally suited to the existing signal transmission system an increase in the amount of data over time to change or change.

however the television service is a public company and can not do without looking at the interests and benefits of Viewers go further. It is important that every new service with existing television receivers and display devices are valued can. In particular, the compatibility a system particularly desirable to deliver old and new services simultaneously or a new service, which can be received by existing and advanced receivers.

It understands that either new digital television broadcasting system to be implemented with respect to An increase in data must be designed to meet future requirements and technical advantages, and also with regard to one compatible effect for existing receivers to receive transmissions.

The expandability and the compatibility performance of prior art digital television systems will be explained.

It a digital television satellite system is known in which NTSC TV signals at about 6 Mpbs are compressed by time division modulation by QPSK and transferred to 4 to 20 channels be while High definition television signals on a single channel become. Another digital high-definition television system is provided in the high-definition television video data, which are compressed to as little as 15 Mbps, on a 16 or 32 QAM signal (quadrature amplitude modulation signal) transmitted through ground stations become.

One Such a known satellite system enables high-definition television signals to be displayed on a television Channel in a conventional Worn way, so that a Frequency band equivalent to some channels of NTSC signals is. This causes the corresponding NTSC channels during transmission of the high-definition television signal not available are. Also is the compatibility between NTSC and HDTV receivers or display devices hardly affected, and the data expansion capacity, to adapt to a future, advanced mode needed will be disregarded, emphasized.

One offers such general high definition terrestrial television system a high-definition television service on conventional 16 or 32 GAM signals without any change. For some analog Television service becomes a lot of signal attenuating or shadow areas in its supply area due to structural hindrances, geographical inaccessibility or a signal disturbance of a neighboring station generated. If the TV signal is an analogue Form, it may be more or less in such signal attenuating Although its reproduced image of low quality is. If the television signal has a digital form, it can hardly with an acceptable level within the range become. This disadvantage is especially hostile to the development of any digital television system.

Of the Article "Multi resolution Source And Channel Coding for Digital Broadcasting of HDTV "G K.M.Uz et al. from Signal Processing of HDTV, III, edited by H. Yasude et al. Elsevier, 1992, discloses a dual HDTV signal Resolution, that is modulated using a 64-QAM scheme.

EP-A-0,485,108 discloses a modulation scheme that includes a constellation map used to different levels. error protection for the most important To create data elements.

EP-A-0,485,105 discloses a scheme for encoding HDTV signals by dividing the television signal into two data streams, which then be mapped so that different levels of error protection are created.

EP 0 448 492 A1 discloses a digital data transmission device having at least two protection levels of the type for ensuring the distribution of the data to be transmitted in the form of digital elements in the time-frequency space. The transmitted symbols each consist of a multiplex of N orthogonal carriers modulated by a set of digital elements. Furthermore, channel coding means are provided which have at least two modulation types and / or at least two coding efficiencies.

According to the present Invention will be a signal transmission device as claimed in claim 1, a signal receiving device as in Claim 4 claims a transmission system such as claimed in claim 7 and corresponding methods as in claims 8, 11 and 14 claimed.

The present invention can thereby provide a communication system that for compatible use for existing NTSC and introduction High-definition television services, especially about Satellite, equipped, and also to signal attenuating or To minimize shadow areas of their supply area at the floor.

One Communication system according to the present The invention intentionally varies signal points commonly found in U.S. Pat even intervals distributed to the signal transmission / the Signal reception. For example, if the communication system is on a QAM signal applied, it has two main areas. A transmitter with a Signal input circuit, a modulator circuit for generating number of m signal points in a signal vector field by modulation of a plurality phase shifted carrier waves, wherein an input signal provided by the input circuit is used and a transmitting circuit for transmitting a resultant modulated signal; and a receiver with an input circuit for receiving the modulated signal, a demodulator circuit for demodulating 1-bit signal points of a QAM carrier wave and an output circuit.

At the Operation will be the input signal, which is a first stream of data contains g values and a second data stream, fed to the modulator circuit of the transmitter, where a modified one m-8it QAM carrier wave is generated, which represents m signal points in a vector field. The m signal points are subdivided into g signal point groups to which in each case the g values of the first data stream are assigned. Also data of the second data stream become m / g signal points or subgroups assigned by each signal point group. Then a resulting transmission signal transmitted from the transmission circuit. Likewise, a third data stream can spread.

at the recipient becomes the first data stream of the transmission signal first demodulated by m signal points in a signal space diagram divided into g signal point groups. Then the second one Data stream demodulated by m / g values m / g signal points from each corresponding signal point group for the reconstruction of the first and be assigned to the second data stream. If the receiver at m = g, the g signal point groups are again requested and the g values for demodulation and reconstruction of the first data stream assigned.

At the Receipt of the same transmission signal from the sender can be a receiver, the one with a large format Antenna equipped and the modulation of a big one Data volume capable is to recover the first and the second data stream. A receiver that equipped with a small format antenna and a modulation of a small amount of data capable is, can recover only the first data stream. Accordingly, the compatibility the signal transmission system ensured. If the first data stream is an NTSC television signal or the low frequency band component of a high definition television signal and the second data stream is a high frequency band component of the high-definition television signal is, the modulation receiver can for one small amount of data to reconstruct the NTSC television signal and the modulation receiver for one size Amount of data can be the high-definition remote signal reconstruct. It is understood that a digital NTSC / HDTV service is simultaneously feasible is, taking the compatibility the signal transmission system of the present invention is used.

For example, a sender generates 1 a modified m-bit QAM signal, of which a first, second and third data stream, each carrying n values, the respective signal point groups with a modulator 4 be assigned. The signal can be received and reproduced, namely the first data stream only from a first receiver 23 , the first and second data streams from a second receiver 33 and, overall, the first, second and third streams from a third recipient 43 ,

In particular, a receiver capable of demodulating n-bit data may represent n bits from a multi-bit modulated carrier wave carrying m-6it data, where m> n such that Communication system compatibility and the possibility of future expansion. Also, multi-level signal transmission is possible by shifting the signal points of the QAM so that a zero point of the I-axis coordinates and the Q-axis at the closest signal point is spaced from the zero point by nδ where δ is the closest-point distance of each Axis and n is greater than 1.

Accordingly, a compatible, digital satellite service for the NTSC and the high-definition television system feasible if the first data stream carries an NTSC signal and the Work stream a dinference signal between NTSC and high-definition television wearing. Therefore, the ability to an increase in the amount of data to be transmitted is to be ensured. Also on the ground is his supply area increased during areas with signal attenuation be reduced.

The The present invention will be further described below with reference to FIG to the following description of exemplary embodiments and the accompanying drawings, in which:

1 Fig. 12 is a schematic view of the entire arrangement of the signal transmission system, showing a first embodiment of the present invention;

2 Fig. 10 is a block diagram of a transmitter of the first embodiment;

3 Fig. 15 is a vector diagram showing a transmission signal of the first embodiment;

4 Fig. 15 is a vector diagram showing a transmission signal of the first embodiment;

5 Fig. 13 is a view showing an assignment of binary codes to signal points according to the first embodiment;

6 Fig. 12 is a view showing an assignment of binary codes to signal point groups according to the first embodiment;

7 FIG. 12 is a view showing assignment of binary codes to signal points in each signal point group according to the first embodiment. FIG.

8th Fig. 12 is a view showing another assignment of binary codes to signal point groups and their signal points according to the first embodiment;

9 Fig. 13 is a view showing thresholds of the signal point groups according to the first embodiment;

10 Fig. 15 is a vector diagram of a modified 16 QAM signal of the first embodiment;

11 FIG. 15 is a graphical diagram showing the relationship between the antenna radius r ₂ and the transmission energy ratio n according to the first embodiment; FIG.

12 Fig. 13 is a view showing the signal points of a modified 64 QAM signal of the first embodiment;

13 Fig. 16 is a graphical diagram showing the relationship between the antenna radius r ₃ and the transmission energy ratio n according to the first embodiment;

14 Fig. 12 is a vector diagram showing signal point groups and their signal points of the modified 64 QAM signal of the first embodiment;

15 Fig. 12 is an explanatory view showing the relationship between A ₁ and A _{2 of} the modified 64 QAM signal of the first embodiment;

16 Fig. 15 is a graphical diagram showing the relationship between the antenna radius r ₂ , r ₃ and the transmission energy ratio n ₁₆ , n _64, respectively, according to the first embodiment;

17 Fig. 10 is a block diagram of a digital transmitter of the first embodiment;

18 Fig. 10 is a signal space diagram of a QPSK modulated signal of the first embodiment;

19 Fig. 10 is a block diagram of a first receiver of the first embodiment;

20 Fig. 10 is a signal space diagram of a QPSK modulated signal of the first embodiment;

21 Fig. 10 is a block diagram of a second receiver of the first embodiment;

22 Fig. 15 is a vector diagram of a modified 16 QAM signal of the first embodiment;

23 FIG. 12 is a vector diagram of a modified 64 QAM signal of the first embodiment. FIG.

24 Fig. 10 is a flowchart showing an effect of the first embodiment;

25 (a) and 25 (b) 15 are vector diagrams showing an 8 and a 16 QAM signal of the first embodiment, respectively;

26 Fig. 10 is a block diagram of a third receiver of the first embodiment;

27 Fig. 12 is a view showing signal points of the modified 64 QAM signal of the first embodiment;

28 Fig. 10 is a flowchart showing another effect of the first embodiment;

29 Fig. 12 is a schematic view of the entire arrangement of a signal transmission system showing a third embodiment of the present invention;

30 Fig. 10 is a block diagram of a first video encoder of the third embodiment;

31 Fig. 10 is a block diagram of a first video encoder of the third embodiment;

32 Fig. 10 is a block diagram of a second video encoder of the third embodiment;

33 Fig. 10 is a block diagram of a third video encoder of the third embodiment;

34 Fig. 10 is an explanatory view showing time division multiplexing of D ₁ , D ₂ and D ₃ signals according to the third embodiment;

35 Fig. 10 is an explanatory view showing another time-division multiplexing of D ₁ , D ₂ and D ₃ signals according to the third embodiment;

36 Fig. 10 is an explanatory view showing further time-division multiplexing of D ₁ , D ₂ and D ₃ signals according to the third embodiment;

37 Fig. 12 is a schematic view of the entire arrangement of a signal transmission system showing a fourth embodiment of the present invention;

38 Fig. 10 is a vector diagram of a modified 16 QAM signal of the third embodiment;

39 Fig. 12 is a vector diagram of the modified 16 QAM signal of the third embodiment;

40 FIG. 12 is a vector diagram of a modified 64 QAM signal of the third embodiment; FIG.

41 Fig. 10 is a diagram of the assignment of data components to a time base according to the third embodiment;

42 Fig. 10 is a diagram of the assignment of data components to a time base with the effect of time division multiple access according to the third embodiment;

43 Fig. 10 is a block diagram of a carrier reproduction circuit of the third embodiment;

44 Fig. 15 is a diagram showing the principle of carrier wave reproduction according to the third embodiment;

45 Fig. 10 is a block diagram of a reverse modulation carrier reproducing circuit in the third embodiment;

46 Fig. 15 is a diagram showing an assignment of signal points of the 16-QAM signal of the third embodiment;

47 Fig. 15 is a diagram showing an assignment of signal points of the 64 QAM signal of the third embodiment;

48 Fig. 10 is a block diagram of a carrier reproduction circuit for 16 × multiplication of the third embodiment;

49 FIG. 10 is an exemplary view showing time-division multiplexing of D _V1 , D _H1 , D _V2 , D _H2 , D _V3 and D _H3 signals according to the third embodiment; FIG.

50 Fig. 10 is an explanatory view showing multiple access time-division multiplexing of D _V1 , D _H1 , D _V2 , D _H2 , D _V3 and D _H3 signals according to the third embodiment;

51 Fig. 12 is an explanatory view showing another time division multiplexing of D _V1 , D _H1 , D _V2 , D _H2 , D _V3 and D _H3 signals according to the third embodiment;

52 Fig. 10 is a diagram showing a signal interference region in a conventional transmission method according to the fourth embodiment;

53 Fig. 15 is a diagram showing signal noise regions in a multi-level signal transmission method according to the fourth embodiment;

54 FIG. 12 is a diagram showing signal attenuation areas in the conventional transmission method according to the fourth embodiment. FIG shows;

55 Fig. 12 is a diagram showing signal attenuation regions in the multi-level signal transmission method according to the fourth embodiment;

56 Fig. 12 is a diagram showing a signal interference region between two digital television stations according to the fourth embodiment;

57 Fig. 15 is a diagram showing an assignment of signal points of a modified 4 ASK signal of the fifth embodiment;

58 Fig. 12 is a diagram showing another assignment of signal points of the modified 4 ASK signal of the fifth embodiment;

59 (a) and 59 (b) are diagrams that modify the assignment of signal points of the modified. FIG. 4 shows ASK signals of the fifth embodiment; FIG.

60 Fig. 12 is a diagram showing another assignment of signal points of the modified 4 ASK signal of the fifth embodiment when the S / N rate (S / N ratio) is low;

61 Fig. 10 is a block diagram of a transmitter of the fifth embodiment;

62 (a) and 62 (b) Fig. 15 are diagrams showing frequency distribution profiles of an ASK modulated signal of the fifth embodiment;

63 Fig. 10 is a block diagram of a receiver of the fifth embodiment;

64 Fig. 10 is a block diagram of a video signal transmitter of the fifth embodiment;

65 Fig. 10 is a block diagram of a television receiver of the fifth embodiment;

66 Fig. 10 is a block diagram of another television receiver of the fifth embodiment;

67 Fig. 10 is a block diagram of a television satellite ground receiver of the fifth embodiment;

68 Fig. 15 is a diagram showing an assignment of signal points of an 8 ASK signal of the fifth embodiment;

69 Fig. 10 is a block diagram of a video encoder of the fifth embodiment;

70 Fig. 10 is a block diagram of a video encoder of the fifth embodiment including a divider circuit;

71 Fig. 10 is a block diagram of a video decoder of the fifth embodiment;

72 Fig. 10 is a block diagram of a video decoder of the fifth embodiment including a mixing circuit;

73 Fig. 15 is a diagram showing a time allocation of data components of a transmission signal according to the fifth embodiment;

74 (a) Fig. 10 is a block diagram of a video decoder of the fifth embodiment;

74 (b) Fig. 10 is a diagram showing another time allocation of data components of the transmission signal according to the fifth embodiment;

75 Fig. 15 is a diagram showing a time allocation of data components of a transmission signal according to the fifth embodiment;

76 Fig. 15 is a diagram showing a time allocation of data components of a transmission signal according to the fifth embodiment;

77 Fig. 15 is a diagram showing a time allocation of data components of a transmission signal according to the fifth embodiment;

78 Fig. 10 is a block diagram of a video decoder of the fifth embodiment;

79 Fig. 15 is a diagram showing a time allocation of data components of a three-level transmission signal of the fifth embodiment;

80 Fig. 10 is a block diagram of another video decoder of the fifth embodiment;

81 Fig. 15 is a diagram showing a time allocation of data components of a transmission signal according to the fifth embodiment;

82 Fig. 10 is a block diagram of a video decoder for a D ₁ signal of the fifth embodiment;

83 Fig. 15 is a graphic diagram showing the relationship between the frequency and the time of a frequency-modulated signal according to the fifth embodiment;

84 Fig. 10 is a block diagram of a magnetic recording / reproducing apparatus according to the fifth embodiment;

85 Fig. 15 is a graphic diagram showing the relationship between S / N and the level according to the second embodiment;

86 Fig. 15 is a graphic diagram showing the relationship between S / N and the transmission path according to the second embodiment;

87 Fig. 10 is a block diagram of a transmitter of the second embodiment;

88 Fig. 10 is a block diagram of a receiver of the second embodiment;

89 Fig. 15 is a graphic diagram showing the relationship between S / N and the error rate according to the second embodiment;

90 Fig. 12 is a diagram showing signal attenuation areas in the three-level transmission of the fifth embodiment;

91 Fig. 12 is a diagram showing signal attenuation regions in the four-level transmission of a sixth embodiment;

92 Fig. 15 is a diagram showing the four-level transmission of the sixth embodiment;

93 Fig. 10 is a block diagram of a divider of the sixth embodiment;

94 Fig. 10 is a block diagram of a mixing circuit of the sixth embodiment;

95 Fig. 12 is a diagram showing another four-level transmission of the sixth embodiment;

96 Figure 4 is a view of the signal propagation of a known digital television broadcasting system;

97 Fig. 10 is a view of the signal propagation of a digital television broadcasting system according to the sixth embodiment;

98 Fig. 15 is a diagram showing a four-level transmission of the sixth embodiment;

99 Fig. 15 is a vector diagram of a 16 SRQAM signal of the third embodiment;

100 Fig. 15 is a vector diagram of a 32 SRQAM signal of the third embodiment;

101 Fig. 15 is a graphical diagram showing the relationship between S / N and the error rate according to the third embodiment;

102 Fig. 15 is a graphical diagram showing the relationship between S / N and the error rate according to the third embodiment;

103 Fig. 12 is a graphic diagram showing the relationship between a displacement distance n and S / N required for transmission according to the third embodiment;

104 Fig. 12 is a graphic diagram showing the relationship between a displacement distance n and S / N required for transmission according to the third embodiment;

105 Fig. 12 is a graphic diagram showing the relationship between the signal level and the distance from a transmitter antenna in a terrestrial television service according to the third embodiment;

106 Fig. 15 is a diagram showing a service area of the 32 SRQAM of the third embodiment;

107 Fig. 15 is a diagram showing a service area of the 32 SRQAM signal of the third embodiment;

108 Fig. 15 is a diagram showing a frequency distribution profile of a television signal of the third embodiment;

109 Fig. 16 is a diagram showing a timing of the television signal of the third embodiment;

110 Fig. 15 is a diagram showing a principle of C-CDM of the third embodiment;

111 Fig. 13 is a view showing an assignment of codes according to the third embodiment;

112 Fig. 15 is a view showing an assignment of an extended 36 QAM according to the third embodiment;

113 Fig. 10 is a view showing a frequency assignment of a modulation signal according to the fifth embodiment;

114 Fig. 10 is a block diagram showing a magnetic recording / reproducing apparatus according to the fifth embodiment;

115 Fig. 10 is a block diagram showing a transceiver of a portable telephone according to the eighth embodiment;

116 Fig. 10 is a block diagram showing base stations according to the eighth embodiment;

117 Fig. 10 is a view illustrating communication capacities and traffic distribution of a conventional system;

118 Fig. 12 is a view illustrating communication capacities and traffic distribution according to the eighth embodiment;

119 (a) Fig. 10 is a diagram showing a time slot assignment of a conventional system;

119 (b) Fig. 15 is a diagram showing a time slot allocation according to the eighth embodiment;

120 (a) Fig. 10 is a diagram showing a time slot assignment of a conventional TDMA system;

120 (b) Fig. 15 is a diagram showing a time slot assignment according to a TDMA system of the eighth embodiment;

121 Fig. 10 is a block diagram showing a single-level transmitter / receiver according to the eighth embodiment;

122 Fig. 10 is a block diagram showing a two-level transceiver according to the eighth embodiment;

123 Fig. 10 is a block diagram showing an OFDM type transceiver according to the ninth embodiment;

124 Fig. 10 is a view showing a principle of the OFDM system according to the ninth embodiment;

125 (a) Fig. 15 is a view showing a frequency assignment of a modulation signal of a conventional system;

125 (b) Fig. 15 is a view showing a frequency assignment of a modulation signal according to the ninth embodiment;

126 (a) Fig. 12 is a view showing a frequency assignment of a transmission signal of the ninth embodiment;

126 (b) FIG. 16 is a view showing a frequency assignment of a reception signal according to the ninth embodiment; FIG.

127 Fig. 10 is a block diagram showing a transceiver according to the ninth embodiment;

128 Fig. 10 is a block diagram showing a trellis encoder according to the fifth embodiment;

129 Fig. 13 is a view showing a time allocation of effective character portions and guard intervals according to the ninth embodiment;

130 Fig. 15 is a graphic diagram showing a relationship between S / N rate and error rate according to the ninth embodiment;

131 Fig. 10 is a block diagram showing a magnetic recording / reproducing apparatus according to the ninth embodiment;

132 Fig. 16 is a view showing a recording format of a track on the magnetic tape and a movement of a head;

133 Fig. 10 is a block diagram showing a transceiver according to the third embodiment;

134 is a diagram showing a frequency allocation of conventional television;

135 Fig. 15 is a diagram showing a relationship between service area and picture quality in a three-level signal transmission system according to the third embodiment;

136 Fig. 15 is a diagram showing frequency allocation in the case where the multi-level signal transmission system according to the third embodiment is combined with an FDM;

137 Fig. 10 is a block diagram showing a transceiver according to the third embodiment in which trellis coding is applied;

138 Fig. 10 is a block diagram showing a transmitter / receiver according to the ninth embodiment in which a part of a signal in the low frequency band is transmitted by OFDM.

Detailed description the preferred embodiment

Embodiment 1

A embodiment The present invention will be described with reference to the drawings in question described.

1 shows the entire arrangement of a signal transmission system according to the present invention. A transmitter 1 includes an input unit 2 , a divider unit 3 , a modulator 4 and a transmitter unit 5 , In operation, each input multiple signal is driven by the divider circuit 3 subdivided into three groups, a first data stream D1, a second data stream D2 and a third data stream D3, which then pass through the modulator 4 be modulated before coming from the transmitter unit 5 be sent. The modulated signal is from an antenna 6 through an uplink 7 to a satellite 10 sent where it is from an uplink antenna 11 received and from a transponder 12 is amplified before it from a downlink antenna 13 is sent towards the ground.

The transmission signal then goes down through three downlinks 21 . 31 and 41 to a first 23 , a second one 33 or a third recipient 43 Posted. In the first receiver 23 This is done by an antenna 22 received signal through input unit 24 a demodulator 25 and only its first data stream is demodulated while the second and third data streams are not recovered before moving farther from the output unit 26 to be asked.

Similarly, the second receiver allows 33 in that the first and the second data stream of the signal transmitted by an antenna 32 received and from an input unit 34 supplied by a demodulator 35 is demodulated, and then to a single data stream through a summer 37 is summed, then further from an output unit 36 is transmitted.

The third receiver 43 allows, in total, the first, second and third data streams of the signal from an antenna 42 received and from an input unit 44 is supplied by a demodulator 45 is demodulated and then by a summer 47 is summed into a single data stream, which then continues from an output unit 46 is transmitted.

One sees that the three individual receivers 23 . 33 and 43 their respective modulators have different characteristics so that their from the same frequency band signal of the transmitter 1 demodulated outputs contain data of different sizes. In particular, three different but compatible data may be carried simultaneously on a given frequency band signal to their respective receivers. For example, each of three existing NTSC, HDTV and super HDTV, digital signals is divided into a low, a high and a super high frequency band component with respect to the first, second and third data streams, respectively. Accordingly, the three different television signals can be transmitted on a single-channel frequency band carrier for the simultaneous reproduction of a television picture with a medium, a high or a super high resolution.

In operation, the NTSC television signal is received by a receiver accompanied by a small antenna for the dimention of small amounts of data, the high-definition television signal is received by a receiver accompanied by a medium antenna for demodulating medium-sized data, and the super HDTV signal is received by a receiver accompanied by a large antenna for demodulating large data. Also, as it is in 1 is shown, a digital NTSC television signal containing only the first data stream for the digital NTSC television service, a digital transmitter 51 fed to where it comes from an input unit 52 received and from a demodulator 54 is modulated before it continues from a transmitting unit 55 is sent. The demodulated signal is then received by an antenna 56 via an uplink 57 to the satellite 10 which in turn is sent the same by a downlink 58 to the first recipient 23 sends on the ground.

The first recipient 23 demodulated with its demodulator 24 the modulated digital signal coming from the digital transmitter 51 has been supplied to the original, first data stream signal. Similarly, the same modulated, digital signal from the second 33 or the third recipient 43 be demodulated to the first data stream or NTSC television signal. In summary, the three individual recipients 23 . 33 and 43 all receive and process a digital signal from the existing TV system for playback.

The Arrangement of the signal transmission system will be described in more detail.

2 is a block diagram of the transmitter 1 in which an input signal is sent through the input unit 2 supplied and by the divider circuit 3 is divided into three digital signals containing a first, a second and a third data stream.

Assuming that the input signal is a video signal, its low frequency band component is associated with the first data stream, its high frequency band component with the second data stream, and its super high frequency band component with the third data stream. The three different frequency band signals become a modulator input 61 of the modulator 4 fed. Here modulates or changes a signal point modulation / change circuit 67 the positions of the signal points according to an externally given signal. The modulator 4 is on for amplitude modulation arranged two 90 ° out of phase carriers, which are then summed to a multiple QAM signal. In particular, the signal is from the modulator input 61 a first 62 and a second AM modulator 63 fed. Also, a carrier wave cos (2πfct) generated by a carrier generator directly becomes the first AM modulator 62 and also a π / 2 phase shifter 66 where it is phase-shifted by 90 ° to a shape sin (2πfct) before going to the second AM modulator 63 is transmitted. The two amplitude modulated signals from the first and second AM modulators 62 . 63 be from a summer 65 to a transmission signal which is then sent to the transmission unit 5 will ask for output. This method is well known and will not be further explained.

The QAM signal will now be described in a general 8x8 or 16 state training, with the first quadrant of a spatial diagram in FIG 3 Reference is made. The output signal of the modulator 4 becomes a sum vector of two vectors one 81 . 82 , Acos2πfct and Bcos2πfct, which represent the two 90 ° out of phase carriers, respectively. If the point of a sum vector remote from the zero point represents a signal point, that has 16 QAM signal 16 Signal points determined by a combination of four horizontal amplitude values a ₁ , a ₂ , a ₃ , a ₄ and four vertical amplitude values b ₁ , b ₂ , b ₃ , b ₄ .

The first quadrant in 3 contains four signal points 83 at C ₁₁ , 84 at C ₁₂ , 85 at C ₂₂ and 86 at C ₂₁ .

C ₁₁ is a sum vector of a vector Da ₁ and a vector Db ₁ and is thus expressed as C ₁₁ = a ₁ cos2πfct -b ₁ sin2πfct = Acos (2πfct + dπ / 2).

It is now assumed that the distance between 0 and a ₁ at the orthogonal coordinates of 3 A ₁ is between a ₁ and a ₂ A ₂ , between 0 and b ₁ B is ₁ and between b ₁ to b ₂ B ₂ .

As it is in 4 4, the 16 signal points are assigned as vector coordinates, each point representing a four-bit pattern, thus allowing transmission of a four-bit data per period or time slot.

5 represents a common assignment of two-bit patterns to the 16 signal points.

If the distance between two adjacent signal points is large, it will be readily recognized by the receiver. Therefore, it is desirable to space the signal points at longer intervals. When two particular signal points are allocated close to each other, they are hardly discriminated and the error rate is increased. Therefore, it is most preferable to have the signal points spaced at equal intervals as shown in FIG 5 is shown in which the 16 QAM signal is determined by A ₁ = A _2/2 .

The transmitter 1 of the embodiment is configured to divide an input digital signal into first, second and third data or bitstreams. The 16 signal points or groups of signal points are divided into four groups. Then, 4 two-bit patterns of the first data stream are assigned to the four signal point groups, respectively, as shown in FIG 6 is shown. In particular, when the two-bit pattern of the first data stream 11 is one of four signal points of the first. Signal point group 91 in the first quadrant depending on the content of the second data stream selected for transmission. Similarly, if it is 01, a signal point of the second signal point group 92 selected and sent in the second quadrant. If it is 00, a signal point becomes the third signal point group 93 in the third quadrant, and when it is 10, a signal point becomes the fourth group of signal points 94 sent in the fourth quadrant. Also, there are 4 two-bit patterns in the second data stream of the 16 QAM signal, or 16 four-bit patterns in the second data stream of a 64-state QAM signal, four signal points or signal sub-groups of each of the four signal point groups 91 . 92 . 93 . 94 each assigned as it is in 7 is shown. It should be understood that the association between any two quadrants is symmetrical. The assignment of the signal points to the four groups 91 . 92 . 93 . 94 is determined by the priority of the two-bit data of the first data stream. As a result, two-bit data of the first data stream and two-bit data of the second data stream can be independently transferred. Also, the first data stream is demodulated using a general QPSK receiver having a given antenna sensitivity. As the antenna sensitivity is greater, a modified type of the 16QAM receiver of the present invention receives the first and second data streams with equal success and demodulates them.

8th shows an example of the assignment of the first and the second data stream to two-bit patterns.

When the low frequency band component of a high definition television video signal is assigned to the first data stream and the high frequency component is assigned to the second data stream, the QPSK receiver can generate an NTSC level image from the first data stream, and the 16- or 64-state QAM receiver can generate a high-definition television image from a composite playback signal of the first and second data streams.

Since the signal points are allocated at equal intervals, a threshold distance is developed in the QPSK receiver between the coordinate axes and the shaded area of the first quadrant, as shown in FIG 9 is shown. When the threshold _distance A is _T0 , a QPSK signal having an amplitude of A _{T0 is} successfully received. However, the amplitude must be increased to a value three times greater or 3A _T0 to transmit a 16 QAM signal while maintaining the threshold _distance A _T0 . In particular, the energy required to transmit the 16 QAM signal is nine times greater than that required to transmit the QPSK signal. Also, when the QPSK signal is sent in a 16 QAM mode, the waste of energy is high and the reproduction of a carrier signal becomes troublesome. Above all, the energy available for satellite transmission is not plentiful but strictly limited to minimal use. Therefore, no signal transmission systems with high power consumption are practically used until more power is available for satellite transmission. It is expected that a large number of QPSK receivers will be introduced to the market when digital television is soon in use. After the introduction on the market, the QPSK receivers are hardly moved to models of greater sensitivity because the distance of the signal receiving characteristic between the two models, the old and the new, is large. Therefore, the transmission of QPSK signals must not be abandoned. In this regard, a new system is absolutely required for transmitting signal point data of a quasi QPSK signal in the 16 QAM mode using less energy. On the other hand, the limited power at a satellite station degrades the entire transmission system.

The present invention resides in a multiple signal level arrangement in which the four signal point groups 91 . 92 . 93 . 94 be allocated at a greater distance from each other as it is in 10 is shown to minimize the power consumption required for 16 QAM modulation of quasi QPSK signals.

To clarify the relationship between the signal reception sensitivity and the transmission power becomes the configuration of the digital transmitter 51 and the first recipient 23 more detail with reference to. 1 described.

The digital transmitter 51 and the first recipient 23 are formed of a known type for data transmission or video signal transmission, for example in a television service. As it is in 17 shown is the digital transmitter 51 a QPSK transmitter, which is the multi-bit QAM transmitter 1 who in 2 shown is equivalent without AM modulation capability. In operation, an input signal is passed through an input unit 52 a modulator 54 where it passes through a Modulator input 121 divided into two components. The two components then become a first two-phase modulator circuit 122 for phase modulation of a base carrier and a second two-phase modulator circuit 123 transmitted to the phase modulation of a carrier which is phase-shifted by 90 ° relative to the base support. The two outputs of the first and second two-phase modulator circuits 122 . 123 are then by a summer 65 is added to a composite, modulated signal further from a transmitter unit 55 is transmitted.

The resulting modulated signal is in the spatial diagram of FIG 18 shown.

It is known that the four signal points are allocated at equal intervals to achieve optimal energy utilization. 18 represents an example where the four signal points 125 . 126 . 127 . 128 4 two-bit pattern 11, 01, 00 and 10 represent. It is also for successful data transmission from the digital sender 51 to the first recipient 23 desired that the QPSK signal from the digital transmitter 51 has an amplitude of not less than a given level. In particular, if the minimum amplitude of the QPSK signal, that for transmission from the digital transmitter 51 to the first recipient 23 with QPSK mode, or the distance between 0 and a ₁ in 18 is equal to A _T0 , the first receiver 23 successfully receive any QPSK signal having an amplitude greater than A _T0 .

The first recipient 23 is trained to be with his antenna 22 small diameter receives a desired or QPSK signal from the transmitter 1 or the digital sender 51 each by the transponder 12 of the satellite 10 sent and with the demodulator 24 is demodulated. In particular, the first receiver 23 essentially designed to receive a digital television or data communication signal in QPSK or 2 PSK Mlodus.

19 is a block diagram of the first receiver 23 in which an input signal coming from the antenna 22 from the satellite 12 received, a carrier extraction circuit 131 where a carrier wave is demodulated, and a π / 2 phase shifter 132 is fed, where a 90 ° phase-shifted carrier wave is demodulated. Also, the two quadrature components of the input signal from a first 133 and a second phase determination circuit 134 each detected and each a first 136 and a second discriminator / demodulation circuit 137 fed. The two demodulated components are identified by their respective discriminator / demodulation circuit 136 and 137 , which are separated in time slot units by means of synchronizing signals from a synchronizing extraction circuit 135 have been distinguished, a first data stream extraction unit 232 where they are summed into a first data stream signal, which is then output from the output unit 26 is delivered.

The input signal to the first receiver 23 will now be more in detail with reference to the vector diagram of 20 explained. That from the first receiver 23 from the digital transmitter 51 Received QPSK signal is expressed in an ideal shape without transmission distortion and noise, with four signal points 151 . 152 . 153 . 154 to be used in 20 are shown.

In practice, the real four signal points appear in particular as each extended areas around the ideal signal positions 151 . 152 . 153 . 154 around because of noise, amplitude distortion or a phase error developed during transmission. When a signal point is shifted unfavorably from its original position, it is hardly discriminated from its neighboring signal point and the error rate is thus increased. As the error rate increases to a critical level, the data becomes less accurate. To allow data rendering to a maximum acceptable level of error rate, the distance between any two signal points should be wide enough to be distinguished from one another. If the distance 2A is ₂₀ , the signal point must be 151 of a QPSK signal near a critical error value in a first discrimination region 155 stay by the hatching of the 20 is denoted by and | 0 - a _R1 | ≧ A ₀ and | 0 - b _R1 | ≧ A _{R0 is} determined. This allows the signal transmission system to reproduce carrier waves and thus to demodulate a desired signal. If the minimum radius of the antenna 22 is set to, the transmission signal may be received with a value larger than a given value from any receiver of the system. The amplitude of a QPSK signal of the digital transmitter 51 , in the 18 is minimal at A _T0 and thus the minimum amplitude A _{R0 of} a QPSK signal from the first receiver 23 is to be received, determined to be equal to A _T0 . As a result, the first receiver 23 receive and the QPSK signal from the digital sender 51 demodulate at the maximum acceptable value of the error rate when the radius of the antenna 22 is greater than r ₀ . When the transmit signal is in a modified 16 or 64 state QAM mode, it may be the first receiver 23 find it difficult to reproduce its carrier wave. To compensate, the signal points are increased to eight, which are assigned at angles of (π / 4 + nπ / 2), as in 25 -A, and its carrier wave is reproduced by a 16 × multiplication technique. Also, if the signal points 16 Places allocated at angles of nπ / 8, as in 25 -B, the carrier of a quasi QPSK mode 16 QAM modulated signal with the carrier extraction circuit 131 which is modified to perform a 16 × frequency multiplication. At this time, the signal points should be in the transmitter 1 be arranged to satisfy A ₁ / (A ₁ + A ₂ ) = tan (π / 8).

Here, a case of receiving a QPSK signal is considered. As with the type used by the signal point modulation / change circuit 67 is executed in the transmitter which is in 2 is shown, it is also possible to modulate the positions of the signal points of the QPSK signal, which in 18 is shown (amplitude modulation, pulse modulation or the like). In this case, the signal point demodulating unit demodulates 138 in the first receiver 23 the position-modulated or position-changed signal. The demodulated signal is output together with the first data stream.

The 16 PSK signal of the transmitter 1 will now be with reference to the vector diagram of 9 explained. When the horizontal vector distance A _{1 of} the signal point 83 greater than A _T0 the minimum amplitude of the QPSK signal of the digital transmitter 51 is, the four signal points remain 83 . 84 . 85 . 86 in the first quadrant of the 9 in the shaded or first reception area 87 of the QPSK signal. If it is from the first receiver 23 is received, the four points of the signal in the first discrimination region of the vector field appearing in 20 is shown. Therefore, any of the signal points 83 . 84 . 85 . 86 of the 9 to the signal level 151 of the 20 through the first receiver 23 are shifted so that the two-bit pattern of 11 is assigned to a corresponding time slot. The two-bit pattern of 11 is identical to 11 of the first group of signal points 91 or the first data stream of a signal from the transmitter 1 , In the same way, the first data stream is reproduced at the second, third or fourth quadrant. As a result, the first receiver recovers 23 Two-bit data of the first data stream from the plurality of data streams in a 16, 32 or 64 state QAM signal transmitted by the transmitter 1 is transmitted. The second and third data stream are in four segments of the signal point group 91 and thus do not affect the demodulation of the first data stream. However, they can affect the reproduction of a carrier wave, and a setting described later is required.

When the transponder of a satellite is supplying abundant energy, the aforementioned technique of 16- to 64-state QAM mode transmission becomes feasible. However, the satellite's transponder in any existing satellite transmission system is severely limited in power supply due to its compact size and solar battery capability. If the transponder or the satellite is increased in size, thus in weight, the cost of firing goes up. These disadvantages are barely eliminated by conventional techniques until the cost of launching a satellite rocket is reduced to a significant level. In the existing system, a common communications satellite provides as little as 20 watts of power, and a standard television / television satellite provides 100 watts to 200 watts at best. To transmit such a QPSK signal in symmetric 16-state QAM mode, as shown in FIG 9 is shown, the minimum signal point spacing of 3A _{T0 is} required when the 16 QAM amplitude is expressed by 2A ₁ = A ₂ . Thus, the energy required for the purpose is nine times greater than that required to transmit a conventional QPSK signal to maintain compatibility. Also, even a conventional satellite transponder can hardly provide power to enable such a small antenna at the first QPSK receiver to receive a transmitted signal therefrom. For example, in the existing 40W system, 360W are needed for proper signal transmission and this becomes unrealistic in terms of cost.

It It goes without saying that the QAM technology has a symmetrical signal state is most effective if the receivers equipped with antennas of the same size be used according to a given transmission power. A however, other novel technology is being used with the receivers with different sizes Antennas equipped are preferred.

More accurate said, while the QPSK signal from a common low-cost receiver system can be received with a small antenna, the 16 QAM signal from a high-quality, expensive, multi-bit modulation receiver system medium or large format Antenna which is designed to receive extremely valuable services, e.g. HDTV conversations to deliver to a specific person who invests more money. This allows that QPSK and 16 QAM signals if desired is transmitted with 64 DMA simultaneously with the help of a small increase in transmission power can be.

For example, the transmit power can be kept low if the signal points at A ₁ = A _{2 are} allocated, as in FIG 10 is shown. The amplitude A (4) for transmission of QPSK data is represented by a vector 96 expressed, which is equivalent to the square root of 2A ₁ ² . The amplitude A (16) of the entire signal is represented by a vector 96 expressed as the square root of (A ₁ + A ₂ ) ² + (B ₁ + B ₂ ) ^{2 is} equivalent. Then | A (4) | 2 = A 1 2 + B 1 2 = A T0 2 + A T0 2 = 2A T0 2 | A (16) | 2 = (A 1 + A 2 ) 2 + (B 1 + B 2 ) 2 = 4A T0 2 + 4A T0 2 = 28A T0 2 | A (16) | / | A (4) | = 2

Accordingly, the 16 QAM signal may become twice the amplitude and four times greater in transmission power than those required for the QPSK signal. A modified 16QAM signal in accordance with the present invention is not demodulated by a conventional receiver designed for a balanced, equally spaced signal point QAM. However, it can work with the second receiver 33 be demodulated when two thresholds A ₁ and A _{2 are} predetermined to have appropriate values. In 10 is the minimum distance between two signal points in the first section of the first signal point group 91 A ₁ and A ₂ / 2A ₁ are made compared to the distance of 2A ₁ from QPSK. Then, since A ₁ = A ₂ , the distance becomes 1/2. This explains that the signal reception sensitivity must be twice greater for the same error rate and four times greater for the same signal level. To have a four times greater value of sensitivity, the radius r _{2 of} the antenna must be 32 of the second receiver 33 twice larger than the radius r _{1 of} the antenna 22 of the first recipient 23 be such that r ₂ = 2r _{1 is} satisfied. For example, the antenna has 32 of the second receiver 33 a diameter of 60 cm when the antenna 22 of the first recipient 23 is equal to 30 cm. In this way, the second data stream representing the high frequency component of a high definition television signal is carried on a single channel and successfully demodulated. If the second receiver 33 receives the second data stream or a higher data signal, its owner can enjoy a profit of its larger investment. Therefore, the second receiver 33 be accepted with a higher price. Since the minimum energy for transmission of QPSK data is predetermined, the ratio n _{16 of} the modified 16 APSK transmission energy to the QPSK transmission energy with respect to the antenna radius r _{2 of} the second Emp catcher 33 calculated using a ratio between A ₁ and A ₂ , as shown in 10 is shown.

In particular, n _{16 is expressed} by ((A ₁ + A ₂ ) / A ₁ ) ² , which is the minimum energy for transmission of QPSK data. Since the signal-to-space ratio suitable for modified 16 QAM reception is A ₂ , the signal-to-space ratio for a QPSK reception is equal to 2A, and the signal-to-space ratio is A ₂ / 2A ₁ , so that the antenna radius r _{2 is} determined in 11 is shown in the the curve 101 the relationship between the transmission power ratio n ₁₆ and the radius r _{2 of} the antenna 22 of the second receiver 23 represents.

Also gives the point 102 the transmission of a conventional 16 QAM in the equally spaced signal state mode, where the transmit power is nine times greater and thus no longer practical. As it is from the curve of 11 Obviously, the antenna radius r _{2 of} the second receiver 23 can not be further reduced even if n _{16 is increased} more than five times.

The transmission power at the satellite is limited to a small value, and thus n _{16 is} preferably not more than five times the value as shown by hatching of the value 11 is specified. The point 104 within the hatched area 103 indicates, for example, that the antenna radius r ₂ is adapted with a value twice as large to a 4 × value of the transmission power. Also, the point represents 105 that the transmission power should be doubled when r _{2 is} about 5 × larger. These values are all within a feasible range.

The value of n ₁₆ which is not larger than 5 × the value is expressed by using A ₁ and A ₂ as: n 16 = ((A 1 + A 2 ) / A 1 ) 2 ≦ 5 therefore A ₂ ≦ 1.23A ₁ .

If the distance between any two signal point group sections that in 10 2A (4) and the maximum amplitude is 2A (16), A (4) and A (16) -A (4) are proportional to A ₁ and A _2, respectively. Therefore, (A (16)) ² ≦ 5 (A (14)) ^{2 is} produced.

The effect of a modified 64 ASPK transmission is described as the third receiver 43 can perform a 64-state QAM demodulation.

12 is a vector diagram in which each signal point group section 16 Signal points compared to 4 signal points of the 10 contains. The first signal point group section 91 in 12 has a 4 × 4 matrix of 16 signal points, at equal intervals including the point 170 allocated. To be compatible with QPSK, A ₁ ≧ A _T0 must be satisfied. If the radius of the antenna of the third receiver 43 is equal to R ₃ and the transmission power is n ₁₆ , the equation is expressed as: r 3 2 = {6 2 / (n - 1)} r 1 2

This relationship between r ₃ and n for a 64 QAM signal is also shown in the graph of FIG 13 shown.

It is understood that the signal point assignment, which in the 12 shown, allows the second receiver 33 only two-bit pattern of QPSK data is demodulated. Therefore, in order to have compatibility between the first, second and third receivers, it is desirable that the second receiver 33 is configured to demodulate a modified 16 QAM format from the 64 QAM modulated signals.

The compatibility between the three individual receivers can be accomplished by a three-level grouping of the signal points as shown in FIG 14 is shown. The description will be made with respect to the first quadrant by using the first signal point group section 91 represents the two-bit pattern with 11 of the first data stream.

In particular, a first subsection is created 181 in the first signal point group section 91 associated with the two-bit pattern with 11 of the second data stream. Likewise, a second 182 , a third one 183 and a fourth subsection 184 each assigned 01, 00 or 10 thereof. This assignment is identical to the one in 7 is shown.

The signal point allocation of the third data stream will now be described with reference to the vector diagram of FIG 15 explained; that shows the first quadrant. As shown, the four signal points represent 201 . 205 . 209 . 213 two-bit pattern with 11 represents the signal points 202 . 206 . 210 . 214 represent 01, the signal points 203 . 207 . 211 . 215 represent 00 and the signal points 204 . 208 . 212 . 216 Accordingly, the two-bit patterns of the third data stream may be transmitted separately from the first and second data streams. In other words, two-bit data of three different signal levels can be transmitted, respectively.

It should be understood that the present invention not only allows the transmission of six-bit data, but also accommodates the reception of three, two-bit, four-bit and six-bit data bit length with their respective receivers while maintaining signal compatibility between the three levels.

The Signal point allocation to provide compatibility between the three levels will be described.

As it is in 15 A ₁ ≧ A _{T0 is} essential for the first receiver 23 can receive the first data stream.

It is necessary to space any two signal points from each other with such a distance that the subsection signal point, eg 182 . 183 . 184 of the second data stream, which in 15 is shown from the signal point 91 can be distinguished in 10 is shown.

15 shows that they are spaced at 2 / 3A ₂ . In this case, the distance is between two signal points 201 and 202 in the first subsection 181 equal to A ₂ / 6th The transmission power used for signal reception with the third receiver 43 is needed is now calculated. If the radius of the antenna 32r , is and the required transmission power is equal to n ₆₄ times the QPSK transmission power, the equation is expressed as: r 3 2 = (12r 1 ) 2 / (n - 1)

This relationship is also through the curve 211 in 16 designated. For example, if the transmit power 6 or 9 times larger than those for a QPSK transmission at that point 223 or 222 is the antenna 32 having a radius of 8 × and 6 × the value, respectively, for receiving the first, second and third data streams for demodulation. When the signal point spacing of the second data stream is close to 2 / 3A ₂ , the relationship between r ₁ and r _{2 is} expressed as: r 2 2 = (3r 1 ) 2 / (n - 1)

Therefore, the antenna must 32 of the second receiver 33 something with its radius being enlarged, as by the curve 223 is specified.

It should be understood that while the first and second data streams will pass through a conventional satellite providing a small signal transmission power, the third data stream may also be polled by a future satellite providing greater signal transmission power without the effect of the first and second second receiver 23 . 33 interrupt or without any need to modify it so that compatibility and progress are

The signal receiving effect of the second receiver 33 will be described first. Compared with the first receiver 23 to receive with a small radius antenna r ₁ and to demodulate the QPSK modulated signal of the digital transmitter 51 or the first data stream of the signal of the transmitter 1 is formed, is the second receiver 33 adapted to perfectly demodulate the 16-signal state two-bit data that is in 10 or the second data stream of the 16 QAM signal from the transmitter 1 , In total, four-bit data including the first data stream can be demodulated. However, the ratio between A ₁ and A ₂ is different for the two transmitters: the two different data are applied to a demodulation control 231 of the second receiver 33 loaded in 21 which in turn supplies its respective thresholds to the demodulation circuit for AM demodulation.

The block diagram of the second receiver 33 in 21 is similar in basic construction to that of the first receiver 23 who in 10 is shown. The difference is that the radius r _{2 of} the antenna 32 greater than r _{1 of} the antenna 22 is. This allows the second receiver 33 detects a signal component that includes a smaller signal point spacing. The demodulator 35 of the second receiver 33 also contains a first one 232 and a second data stream reproducing unit 233 in addition to the demodulation control 231 , It is a first discriminator / reproduction circuit 136 for AM demodulation of the modified 16 QAM signals. It should be understood that each carrier is a four-bit signal having two, one positive and one negative, thresholds above the zero level. As it is from the vector diagram of the 22 obviously, change. the thresholds depending on the transmission power of a transmitter, since the transmission signal of the embodiment is a modified 16 QAM signal. If the reference threshold is equal to TH ₁₆ , it is determined as shown in FIG 22 shown is: T 16 = (A 1 + A 1 / 2) / (A 1 + A 2 )

The various data for demodulation including A ₁ and A ₂ or TH ₁₆ and the value m for the multi-bit modulation are also provided by the transmitter 1 transmitted as they are carried in the first data stream. The demodulation control 231 may be configured to recover such demodulation data by a statistical method of the received signal.

One way to determine the shift factor A ₁ / A ₂ is with reference to FIG 26 described. A change in the shift factor A ₁ / A ₂ causes a change in the threshold value. An increase of a difference of a value A ₁ / A _{2 set} on the receiver side from a value A ₁ / A _{2 set} on the transmitter side increases the error rate. Referring to 26 may be the demodulated signal from the playback unit 233 for the second data stream to the demodulation controller 231 be fed back to shift the shift factor A ₁ / A ₂ in one direction to reduce the error rate. With this configuration, the third receiver 43 do not demodulate the shift factor A ₁ / A ₂ , so that the circuit construction can be simplified. Further, the transmitter can not transmit the shift factor A ₁ / A ₂ , so that the transmission capability can be increased. This technique can also be applied to the second receiver 33 be applied.

The demodulation control 231 has a memory 231 to store therein different thresholds (ie, the shift factors, the number of signal points, the synchronous rules, etc.) corresponding to different channels of the television. When one of the channels is received again, the values corresponding to the receiving channel are read from the memory to thereby quickly stabilize the reception.

When the demodulation data is lost, the demodulation of the second data stream is hardly performed. This will be explained with reference to a flowchart shown in FIG 24 is shown.

Even if the demodulation data is not available, the demodulation of the QPSK at step 313 and the first data stream at the step 301 be executed. At the step 302 be the demodulation data, by the playback unit 232 for the first data stream, to the demodulation controller 231 transfer. If m equals 4 or 2 at the step 303 is, triggers the demodulation control 231 the demodulation of QPSK or 2 PSK at the step 313 out. If not, the method moves to the step 310 , At the step 305 Two threshold values TH ₈ and TH _{16 are} calculated. The threshold value TH ₁₆ for AM demodulation becomes the step 306 from the demodulation controller 231 the first 136 and the second discriminator / reproduction circuit 137 fed. Therefore, the demodulation of the modified 16 QAM signal and the reproduction of the second data stream at step 307 respectively. 315 be executed. At the step 308 the error rate is examined, and if high, the method returns to the step 313 back to repeat the QPSK demodulation.

As it is in 22 shown are the signal points 85 . 83 while aligned on a line at an angle of cos (ωτ + nπ / 2) 84 and 86 are next to the line. Therefore, the feedback from a second data stream carrying carrier wave data, from the playback unit 233 for the second data stream to a carrier return circuit 131 executed so that no carrier at the time of the signal points 84 and 86 must be won.

The transmitter 1 is configured to provide carrier sync signals at intervals of a given time with the first data stream for the purpose of equalizing for non-demodulation of the second data stream. The carrier sync signal allows the signal points 83 and 85 of the first data stream independently of the demodulation of the second data stream. Therefore, the reproduction of the carrier wave by the transmitted carrier data to the carrier reproduction circuit 131 to be triggered.

It will then be at the step 304 of the flowchart of 24 examines whether or not m is equal to 16 upon receipt of such modified 64 QAM signal, as shown in FIG 23 is shown. At the step 310 it is also examined whether m is greater than 64 or not. When at the step 311 is determined that the received signal has no arrangement with equally spaced signal points, the method goes to step 312 , The signal point distance TH _{64 of} the modified 64 QAM signal is calculated from: TH 16 = (A 1 + A 2 / 2) / (A 1 + A 2 )

This calculation is equivalent to that of TH ₁₆ , but its resulting spacing between signal points is smaller.

If the signal point spacing in the first subsection 181 is equal to A ₃ , the distance between the first 181 and the second subsection 182 expressed by (A ₂ - A ₃ ). Then it will be. the average distance (A ₂ - 2A ₃ ) / (A ₁ + A ₂ ), which is referred to as d ₆₄ . If d _{64 is} less than T ₂ , which is the signal point discrimination capability of the second receiver 33 2, any two signal points in the section will hardly be distinguished from each other. This assessment will be at the step 313 executed. If d _{64 is} outside an allowable range, the method goes to the step 313 back to the demodulation of the QPSK mode. If d _{64 is} within the range, the method goes to the step 305 continue to demodulation of 16 QAM at the step 307 to allow. When at the step 308 if it is determined that the error rate is too high, the process goes to the step 313 back to the demodulation of the QPSK mode.

If the transmitter 1 a modified 8 QAM Signal supplies, as it is in 25 -A, in which all the signal points are at angles of cos (2πf + n · π / 4), the carrier waves of the signal are extended to the same phase and thus are very easily reproduced. Meanwhile, two-bit data of the first data stream is demodulated with the QPSK receiver, while one-bit data of the second data stream is demodulated with the second receiver 33 can be demodulated, and the entire three-bit data can be reproduced.

The third receiver 43 will be described in more detail. 26 shows a block diagram of the third receiver 43 similar to that of the second receiver 33 in 21 , The difference is that a playback unit 234 for a third data stream, and also the discriminator / player circuit has the ability to detect eight-bit data. The antenna 42 of the third recipient 43 has a radius r ₃ greater than r ₂ so that state signals can be demodulated at a smaller pitch, eg 32 or 64 state QAM signals. For demodulation of the 64 QAM signal, the first discriminator / reproduction circuit must 136 Recognize 8 digit digits of the detected signal, including seven different thresholds. Since one of the thresholds is zero, three are included in the first quadrant.

27 shows a spatial diagram of the signal in which the first quadrant contains three different thresholds.

As it is in 27 3, when the three normalized threshold values TH1 ₆₄ , TH2 ₆₄ and TH3 are ₆₄ , they are expressed by: TH1 64 = (A 1 + A 3 / 2) / (A 1 + A 2 ) TH2 64 = (A 1 + A 2 / 2) / (A 1 + A 2 ) and TH3 64 = (A 1 + A 3 - A 3 / 2) / (A 1 + A 2 ).

By an AM demodulation of a phase detection signal can be reproduced using the three thresholds, the third data stream as the first and the second data stream with 21 have been declared. The third data stream contains eg four signal points 201 . 202 . 203 . 204 at the first subsection 181 who in 23 showing 4 values of two-bit patterns. Therefore, six digits or modified 64 QAM signals can be demodulated.

The demodulation control 231 determines the pitches m, A ₁ , A ₂ and A ₃ from the demodulation data contained in the first data stream received from the re-input unit 232 has been demodulated for the first data stream, and calculates the three threshold values TH1 ₆₄ , TH2 ₆₄ and TH3 ₆₄ , which then the first 136 and the second discriminator / reproduction circuit 137 are supplied, so that the modified 64 QAM signal is demodulated with certainty. Also, if the demodulation data has been scrambled, the modified 64 QAM signal may be demodulated only with a particular or subscriber receiver. 28 Fig. 10 is a flowchart illustrating the effect of demodulation control 231 for modified 64 QAM signals. The difference from the demodulation chart of the 16 QAM used in 24 is shown is explained. The procedure moves from the step 304 to the step 320 , where it is examined whether m = 32 or not. When m = 32, the demodulation of 32 QAM signals at the step 322 executed. If not, the method moves to the step 321 where it is examined whether m = 64 or not. If so, A ₃ becomes at step 323 examined. If A _{3 is} less than a predetermined value, the process moves to the step 305 and the same sequence as the 24 is running. When at the step 323 is judged that A _{3 is} not smaller than the predetermined value, the method goes to the step 324 where the thresholds are calculated. At the step 325 the calculated threshold values are applied to the first and second discriminator / reproduction circuits, and at step 326 the demodulation of the modified 64 QAM signal is performed. Then the first, second and third data streams are taken at step 327 played. At the step 328 the error rate is examined. If the error rate is high, the method moves to the step 305 where the 16 QAM demodulation is repeated, and if it is low, the demodulation of the 64 QAM continues.

The Effect of carrier wave reproduction, the for execution a satisfactory demodulation process is needed, will now be described. The scope of the present invention includes playback the first data stream of a modified 16 or 64 QAM signal using a QPSK receiver. However, there is a common one QPSK receiver rarely carrier waves again, so that he fails to perform a proper demodulation. To compensate for some Embodiments on the side of the transmitter and the receiver necessary.

Two compensation techniques are provided in accordance with the present invention. A first technique relates to the transmission of signal points aligned at angles of (2n-1) π / 4 at intervals of a given time. A second technique provides for the transmission of signal points at intervals of an angle of nπ / 8 are ordered.

According to the first technique, the eight signal points, including 83 and 85 aligned at angles of π / 4, 3π / 4, 5π / 4 and 7π / 4, as in 38 is shown. In operation, at least one of the eight signal points during the Synchronzeitschlitzperioden 452 . 453 . 454 . 455 transmitted at equal time intervals in a time slot interval 451 arranged in the time diagram of the 38 is shown. Any desired signal points are transmitted during the other time slots. The transmitter 1 is also adapted to data for the time slot interval the synchronous time data area 499 a synchronous data block, as shown in 41 is shown.

The content of a transmission signal will be described in more detail with reference to FIG 41 explained. The time slot group 451 that the synchronous time slots 452 . 453 . 454 . 455 contains, represents a uniform data stream or block 491 representing data D _n .

The Synchronous time slots in the signal are at equal intervals arranged by the time slot interval or the synchronous time data are determined. Dahe will, if the arrangement the synchronizing time slots is detected, the reproduction of carrier waves Slot by slot executed, by taking the synchronous time data from their respective time slots be won.

Such synchronous data S is in a sync block 493 included at the head of a data block 492 is provided, which consists of a number of synchronous time slots, by the hatching in 41 Accordingly, the data to be recovered for carrier wave reproduction increases so that the QPSK receiver can reproduce the desired carrier waves with greater accuracy and effectiveness.

The sync block 493 includes synchronous data areas 496 . 497 . 498 ... containing synchronous data S1, S2, S3 each including unique words and demodulation data. The allocation area 499 for the phase sync signal is at the end of the sync block 493 provided that contains a Date I _T , the information about the interval arrangement and the assignment of the synchronous time slots includes.

The signal point data in the phase sync slot has a certain phase and thus can be reproduced by the QPSK receiver. Accordingly, I _T in the allocation area 499 are recovered for the phase synchronizing signal without error, so that the reproduction of carrier waves is ensured with accuracy.

As it is in 41 is shown follows the sync block 493 a demodulation data block 501 which contains demodulation data about threshold voltages needed to demodulate the modified multi-bit QAM signal. These data are essential for demodulation of the multi-bit QAM signal and may be preferred in one range 502 that is part of the sync block 493 is to be included for easier recovery.

42 shows the assignment of signal data for the transmission of burst format signals by a time division multiple access method.

The assignment is from the 41 distinguished by the fact that a hedging period 521 between any two adjacent Dn data blocks 491 . 491 introduced to interrupt the signal transmission. Also, every data block is 491 at the front end of a synchronous area 522 provided so that a data block 492 is formed. During the synchronous area 522 Only the signal points with a phase with (2 - n1) π / 4 will be transmitted. Accordingly, the carrier wave reproduction with the QPSK receiver becomes feasible. In particular, the sync signal and the carrier waves can be reproduced by time division multiple access.

The carrier wave reproduction of the first receiver 23 , in the 19 is shown more in detail with reference to the 43 and 44 explained. As it is in 43 is shown, an input signal through the input unit 24 a synchronous determination circuit 541 supplied, where its synchronization is determined. A demodulated signal from the synchronous determination circuit 541 becomes an output circuit 542 to transmit the first data stream. A date of the assignment data area 499 the phase of the sync signal (in 41 shown) with a. timing controller 543 so that the timing of the synchronous signals of (2n-1) π / 4 data is confirmed and as a phase synchronous control pulse 561 who in 44 to a carrier reproduction control circuit 544 can be questioned. Also, the demodulated signal of the synchronous determination circuit becomes 541 a frequency multiplication circuit 544 where it is multiplied 4 times before going to the carrier reproduction control circuit 544 is transmitted. The resulting signal, which in 44 With 562 , contains a true phase data 563 and other data. As it is in a time chart 564 of the 44 are the phase synchronous time slots 542 , which carry the (2n - 1) π / 4 data, even at equal intervals. In the carrier reproduction control circuit 544 will that signal 562 by the phase synchronous control pulse 561 sampled to a phase scan signal 565 then generate it by a sample-and-hold effect into a phase signal 566 is converted. The phase signal 566 the carrier reproduction control circuit 544 is via a loop filter 546 a voltage controlled oscillator 547 fed, where its relevant carrier wave is reproduced. The reproduced carrier then becomes the synchronous determination circuit 541 cleverly. In this way the signal point data of the (2n - 1) π / 4 phase passing through the shaded areas in 39 is recaptured and used so that a proper carrier wave can be represented by a 4 × or 16 × frequency multiplication. Although a plurality of phases are reproduced at once, the absolute phase of the carrier can be successfully recognized using a unique word corresponding to the synchronous area 496 is assigned in 41 is shown.

To transmit a modified 64 QAM signal as shown in FIG 40 are shown, signal points in the phase synchronizing areas 471 at the (2n - 1) π / 4 phase indicated by hatching, the sync slots 452 etc. assigned. Its carrier can hardly be reproduced with a standard QPSK receiver, but successfully with the first receiver 23 of the QPSK mode provided with the carrier reproduction circuit of the embodiment.

The aforesaid carrier display circuit is of the COSTAS type. A carrier reproduction circuit Reverse modulation type will now be explained according to the embodiment.

45 shows a carrier modulation circuit of the reverse modulation type according to the present invention, in which a received signal from the input unit 24 a synchronizing determination circuit 541 is supplied to produce a demodulated signal. Also, the input signal is through a first delay circuit 591 delayed to a delay signal. The delay signal then becomes a quadrature phase modulator circuit 592 where it is transmitted by the demodulated signal from the synchronizing determination circuit 541 is demodulated back to a carrier signal. The carrier signal is provided by a carrier recovery control circuit 544 a phase comparator 593 fed. One of a voltage controlled oscillator VCO 547 generated carrier wave is through a second delay circuit 594 delayed to a delay signal, which also the phase comparator 593 is supplied. In the phase comparator 594 the back demodulated carrier signal is compared with the phase with the delay signal, so that a phase difference signal is generated. The phase difference signal is passed through a loop filter 546 a voltage controlled oscillator VCO 547 which in turn generates a carrier wave which is arranged in phase with the received carrier wave. In the same way as the COSTAS Carrier / Playback Circuitry, which in 43 is shown, performs a Synchronisierrückgewinnungssteuerschaltung 543 a scanning of signal points in the hatched areas of 39 are included.

Accordingly, the carrier wave of a 16 or 64 QAM signal with the QPSK demodulator of the first receiver 23 be reproduced.

The reproduction of a vehicle wave by 16 × frequency multiplication is explained. The transmitter 1 who in 1 is shown, is a modified 16 QAM signal with assignment of its signal points at nπ / 8 phase, as in 46 is shown to modulate and transmit. At the first receiver 23 who in 19 2, the carrier wave can be reproduced with its as a COSTAS carrier recovery control circuit comprising a 16 × multiplication circuit 661 contains in 48 is shown. The signal points, each with nπ / 8 phase, in 46 are shown at the first quadrant by the action of the 16 × multiplication circuit 661 edited, reducing the carrier by combining a loop filter 546 and a voltage controlled oscillator VCO 541 is reproduced. The absolute phase can also be determined from the 16 different phases by assigning a unique word to the synchronization range.

The configuration of the 16 × multiplication circuit will be described with reference to FIG 48 explained. A sum signal and a difference signal are output from the demodulated signal by an adding circuit 662 or a subtraction circuit 663 generated and then together by a multiplication circuit 664 multiplied by a coc 2θ signal. Also generates a multiplication circuit 665 a sin 2θ signal. The two signals are then passed through a multiplication circuit 646 multiplied by a sin 4θ signal.

Similarly, a sin 8θ signal from the two signals, sin 2θ and cos 2θ, is obtained by the combination of an adder circuit 667 , a subtraction circuit 668 and a multiplication circuit 670 generated. Furthermore, a sin 16θ Singnal by the combination of an adder 671 , a subtraction circuit 672 and a multiplication circuit 673 generated. Then the 16 × multiplication is completed.

By the aforementioned 16 × multiplication, the carrier wave of all signal points of the abgeän of 16 QAM signals in 46 shown successfully without winning certain signal points.

However, the reproduction of the carrier wave of the modified 64 QAM signal included in FIG 47 is shown an increase in the error rate due to a displacement of some signal points from the synchronization ranges 471 lock in.

Two techniques are known to balance the consequences. One is to prevent the transmission of signal points offset from the sync areas. This causes the total amount of transmitted data to be reduced, but allows the design to be facilitated. The other is to provide sync slots as shown in FIG 38 is described. In particular, the signal points in the nπ / 8 Synchronisierphasenbereichen eg 471 and 471a During the period of the corresponding synchronization time slots in the time slot group 451 transfer. This triggers an accurate synchronizing action during the period, so that a phase error is minimized.

As it is now understood allows the 16 × multiplication a simple QPSK receiver that carrier wave one modified Play 16 or 64 QAM signals. Also causes the introduction of Synchronization slots that the Phase accuracy during the reproduction of the carrier waves from a modified one 64 QAM signal increased becomes.

As As stated above, the signal interrogation system of the present invention may be used Invention a plurality of data on a single carrier wave transmitted simultaneously with the multi-signal level arrangement.

More accurate three recipients are said with different levels, the specific characteristics of the signal reception sensitivity and demodulation option provided with respect to a single transmitter, so that any dependent on them from a desired, to be demodulated data size can be selected which is proportional to the price. If the first receiver with low resolution quality and low Price is purchased together with a small antenna can be Owner receive the first data stream of a Übertragungsunssignals and play. If the second receiver with medium resolution quality and medium price purchased together with a middle antenna, can be owner receive the first and the second data stream of the signal and play. If the third receiver with high resolution quality and high Price with a big one Antenna is purchased, its receiver can be the first one altogether receive and reproduce the second and the third data stream of the signal.

If the first recipient is a low-cost digital satellite home television receiver, He is enthusiastically greeted by the majority of viewers. Of the second receiver, which is accompanied by the middle antenna costs more and will not accepted by the average audience, but by certain People watching high-definition television services want to enjoy. The third receiver, the one from the big one Antenna is accompanied, at least before the satellite output is increased for the Home use not suitable and may be affected by Industries used. For example, the third data stream, Super HDTV signals carries over one Transmit satellites to subscriber cinemas, the video tapes thus instead of conventional Play movies and perform the cinema business at low cost.

If the present invention to a television signal transmission service is applied, three images of different quality on one worn single channel shaft and offer each other compatibility. Although itself the first embodiment on a QPSK, a modified one 8 QAM, a modified one 16 QAM and a modified one 64 QAM signal, other signals will also be the same Success used, including a 32 QAM, a 256 QAM, an 8 PSK, a 16 PSK, a 32 PSK signals. It is understood that the present invention not on a satellite transmission system is limited to a terrestrial communication system or a cable transmission system is applied.

Embodiment 2

A second embodiment of the present invention is provided in which the multi-level physical configuration of the first embodiment is subdivided into small sub-levels by, for example, differentiating the error correction capability so as to form a multi-level logic construction. In the first embodiment, each multilevel channel has different levels in electrical signal amplitude or physical demodulation capability. The second embodiment offers different levels of logical reproducibility, such as the error correction. For example, the data D ₁ in a multilevel channel is divided into two components, D _1-1 and D _1-2 , and D _1-1 is increased more than D _1-2 for discrimination in the error correction capability. Accordingly, since the error determination and correction capability between D _1-1 and D _1-2 is different in demodulation, D _{1-1 can be} successfully reproduced within a given error rate when the S / N level of an original transmission signal is so low is that playback of D _1-2 becomes impossible. This is done by using the logical multi-level design.

More accurate said logical multi-level design is data of a modulated multilevel channel and distances between To differentiate error correction codes by using error correction code with product codes to modify the error-correction capability be mixed. Therefore, a signal with more levels can be transmitted become.

In fact, a D ₁ channel is divided into two subchannels D _1-1 and D _1-2 and a D ₂ channel is divided into two subchannels D _2-1 and D _2-2 .

This will be more specific with reference to 87 in which D _{1-1 is represented} by a lowest S / N signal. When the S / N rate is at most d, three components D _1-2 D _2-1 and D _2-2 can not be reproduced while D _{1-1 is being} reproduced. If S / N is not smaller than c, D _{1-2 can} also be played back. Also, when S / N is b, D _{2-1 is} reproduced, and when S / N is a, D _{2-2 is} reproduced. As the S / N rate increases, the reproducible signal levels are increased in number. The lower the S / N the less reproducible signal levels. This will be in the form of the relationship between the transmission distance and the reproducible S / N value with reference to FIG 86 explained. In general, the S / N value of a received signal is reduced in proportion to the distance of the transmission as it is through the real line 861 in 86 is expressed. It is now assumed that the distance from a transmitting antenna to a receiving antenna is La when S / N = a, Lb when S / N = b, Lc when S / N = c, Ld when S / N = d, and Le is when S / N = e. If the distance from the transmitting antenna is greater than Ld, D _1-1 can be reproduced as shown in FIG 85 shown is where the reception area 462 indicated by the hatching. In other words, D _1-1 can be reproduced within a wide range. Similarly, D _1-2 can be in one range 863 are reproduced when the distance is not more than Lc. In this area 863 who is the area 862 D _1-1 can undoubtedly be reproduced. In a smaller area 850 D _2-1 can be reproduced, and in a smallest area 865 D _2-2 can be reproduced. It should be understood that the various data levels of a channel may be represented according to the degree of reduction in the S / N rate. The logical multi-level configuration of the signal transmission system of the present invention can provide the same effect as a conventional analog transmission system in which the amount of receivable data is gradually reduced as the S / N rate decreases.

The. Construction of the multi-level logic layout is described in which two physical levels and two logic levels are provided. 87 is a block diagram of a transmitter 1 , with the construction essentially identical to the one in 2 is shown and has been described Varhergehend in the first embodiment and will not be explained in detail. The only difference is that the error correction code encoders have been added as ECC encoders in abbreviated form. The divider circuit 3 has four outputs 1-1, 1-2, 2-1 and 2-2, through the four signals D _1-1 , D _1-2 , D _2-1 and D _2-2 , which have been divided from the input signal , to be delivered. The two signals D _1-1 and D _1-2 become two, a main and a slave, ECC encoder 872a . 873a of the first ECC encoder 871a each supplied for conversion into error correction forms.

The main ECC encoder 872a has a larger error correction capability than the sub-ECC encoder 873a , Therefore, D _1-1 can be reproduced at a lower rate of S / N than D _1-2 ; as can be seen from the S / N level diagram of the 85 obviously. In particular, the logic level of D _{1-1 is} less affected by the reduction of S / N than that of D _1-2 . After being coded with the error correction code, D _1-1 and D _1-2 become one summer 874a is summed to a D ₁ signal which is then sent to the modulator 4 is transmitted. The other two signals D _2-1 and D _{2-2 of} the divider circuit 3 are returned to error correction by two, a major and a minor, ECC encoder 872b . 873b a second ECC encoder 871b each coded, and then by a summer 874b is summed to a D ₂ signal which is then sent to the modulator 4 is transmitted. The main ECC encoder 872b has a larger error correction capability than the sub ECC encoder 873b , The modulator 4 in turn, generates from the two input signals, D ₁ and D ₂ , a modulated multi-level signal farther from the transmitting unit 5 is transmitted. It is understood that the output signal from the transmitter 1 has two physical levels D ₁ and D ₂ and also four logic levels D _1-1 , D _1-2 , D _2-1 and D _2-2 based on the two physical levels to provide different error correction capabilities.

The reception of such a multi-level signal will be explained. 88 is a block diagram of a second receiver 33 , which is almost identical to the one in the construction 21 is identical and has been described in the first embodiment. The second receiver 33 which is for receiving multilevel signals from the transmitter 1 who in 87 is shown, further comprises a first 876a and a second ECC encoder 876b in which the demodulation of QAM or ir an AKS, PSK and FSK is executed, if desired.

As it is in 88 is shown, a received signal through the demodulator 35 demodulated into two signals, D ₁ and D ₂ , which then have two divider circuits 3a respectively. 3b where they are divided into four logic levels D _1-1, D _1-2, D _2-1 and D _2-2 . The four signals become the first 876a and the second ECC decoder 876b in which D _{1-1 is} transmitted through a main ECC decoder 877a is error corrected. D _1-2 through a slave ECC decoder 878a , D _2-1 through a main ECC decoder 877b and D _2-2 by a sub ECC decoder 878e before all to the summer 37 sent. At the summer 37 For example, the four error corrected signals, D _1-1 , D _1-2 , D _2-1 and D _2-2 , are summed into a single signal which is then output from the output unit 36 is delivered.

Since D _1-1 and D _2-1 have greater error correction capability than D _1-2 and D _2-2 respectively, the error rate remains lower than a given value, although S / N is quite low, as shown in FIG 85 is shown, and thus an original signal is reproduced successfully.

The effect of distinguishing the error correction capability between the main ECC decoders 877a . 877b and the slave ECC decoder 878a . 878b will now be described in more detail. It is a good idea to have a difference in error correction capability in the sub-ECC decoder using a common coding technique, eg a Reed-Solomon or BCH method having a standard code spacing, and in the main ECC decoder another coding technique in which the distance between the error correction codes is increased using Reed-Solomon code, its product code or other code of great length. A variety of known techniques for increasing the error correction distance must be introduced and will not be discussed. The present invention may be combined with any known technique to achieve the logic multi-level design.

The logic multi-level design will be described in conjunction with a diagram of 89 which illustrates the relationship between S / N and the error rate after the error correction. As it is shown, the straight line represents 881 D _1-1 at S / N and the error rate relationship, and the line 882 represents the same with D _1-2 .

As the S / N rate of an input signal decreases, the error rate after error correction increases. If S / N is lower than a given value, the error rate exceeds a reference value Eth determined by the system design specifications, and no original date is normally reconstructed. When S / N is reduced to less than e; The D ₁ signal fails to be reproduced as it passes through the line 881 from D _1-1 in 89 is expressed. If e ≦ S / N <d, D _{1-1 of} the D ₁ signal shows a larger error rate Eth and is not reproduced.

If S / N is equal to d at the point 885d is, D _1-1, which has a larger error correction capability than D _1-2 , with the error rate is not greater than Eth and can be played back. At the same time, the error rate of D _1-2 remains higher than Eth after the error correction and is no longer reproduced.

If S / N up to c at the point 885c is increased, D _1-2 with the error rate does not become larger than Eth and can be reproduced. At the same time, D _2-1 and D _2-2 remain in no demodulation state. After the S / N Pate has been further increased to b ', the D ₂ signal becomes ready to be demodulated.

If S / N to the point b at the point 885b is increased, D _{2-1 of} the D ₂ signal with the error rate does not become larger than Eth and can be reproduced. At this time, the error rate of D _2-2 remains larger than Eth and is not reproduced. If S / N to a at the point 885a is increased, D _2-2 does not become larger than Eth and can be reproduced.

As described above, the four different logical signal levels divided from two physical levels, D ₁ and D ₂ , by distinguishing the error correction capability between the levels, may be simultaneously transmitted.

Under Use of the logical multi-level embodiment of the present invention Invention accompanied by a multi-level construction in which at least part of the original one Signal is reproduced even when data at a higher level lost, a digital signal transmission is successfully carried out without to lose the beneficial effect of an analog signal transmission at the transferring Data is gradually reduced when the S / N rate is low becomes.

Thanks to today's image data compression techniques, compressed image data can be transmitted in the logical multi-level arrangement to allow a receiver station to reproduce a higher quality image than that of an analog system, even with a signal level not sharply but gradually decreasing ensure signal reception over a larger area. The present invention can provide an additional effect of the multi-layered design, which is hardly performed by a known digital signal transmission system without degrading the high quality image data.

Embodiment 3

The third embodiment The present invention is described with reference to the relevant Drawings described.

29 Fig. 10 is an overall schematic view illustrating the third embodiment in the form of a digital television system. An input video signal 402 a television picture super high resolution becomes an input unit 403 a first video codec 401 fed. Then the signal is switched by a divider circuit 404 divided into three data streams, in a first, second and third, leading to a compression circuit 405 for data compression before they are handed off.

In the same way, other three video input signals 406 . 407 and 408 a second 409 , a third 410 and a fourth video encoder 411 each fed, all of identical construction as the first video encoder 401 are designed for data compression.

The four first data streams from their respective encoders 401 . 409 . 410 . 411 become a first multiplexer 413 , a multiplexer 412 where they are time division multiplexed to a first data stream multiplex signal which is time division multiplexed to a transmitter 1 is supplied.

Part or all of the four second data streams from their respective encoders 401 . 409 . 410 . 411 become a second multiplexer 414 of the multiplexer 412 where they are time-multiplexed to a second data stream multiplex signal representing the sender 1 is supplied. Also, a part or all four third data streams become a third multiplexer 415 where they are time division multiplexed into a third stream multiplexed signal which is then sent to the transmitter 1 is supplied.

The transmitter 1 performs a modulation of the three data stream signals with its modulator 4 in the same way as has been described in the first embodiment. The modulated signals are from a transmitter unit 5 via an antenna 6 and an uplink 7 to a transponder 12 a satellite 10 sent them in turn to three different recipients, including a first recipient 23 , transfers.

That via a downlink 21 transmitted, modulated signal is from a small antenna 22 received with a radius r ₁ and a playback unit 232 for a first data stream of the first receiver 23 supplied, where only its first data stream is demodulated. The demodulated, first data stream is then passed through a first video decoder 421 in a conventional 425 or wide-screen NTSC or video output signal 426 implemented low image resolution.

Also, the modulated signal is transmitted through a downlink 31 is transmitted from a central antenna 32 with a radius r ₂ received and a first 232 and a second playback unit 233 for a data stream of a second receiver 33 supplied, where its first and second data stream are respectively modulated. The demodulated first and second data streams are then summed and processed by a second video decoder 422 in a HTDV or video output signal 427 high resolution and / or video output signals 425 and 426 transformed.

Also, the modulated signal is transmitted through a downlink 41 is transmitted from a large antenna 42 received with a radius r ₃ and a first 232 , a second one 233 and a third stream display unit 234 a third recipient 43 supplied, where its first, second and third data stream are respectively demodulated. The demodulated first, second and third data streams are then summed and passed through a third video decoder 423 into a super high-definition television or video output signal 428 implemented with super large resolution for use in a video theater or cinema. The video output signals 425 . 426 and 427 can also be reproduced, if desired. A common digital television signal is from a conventional digital transmitter 51 transmit, and if it is from the first receiver 23 is received, it will be in the video output signal 426 , such as a low resolution NTSC television signal, converted.

The first video encoder 401 will now be more detailed with reference to the block diagram of 30 explained. A super high resolution input video signal is passed through the input unit 403 the dish circuit 404 where it is divided into four components by a minor band coding method. In particular, the input video signal is converted by passing through a horizontal low-pass filter 451 and a horizontal high pass filter 452 from eg QMF mode, divided into two horizontal frequency components, one low and one high, divided by one half of their quantity by two sub-samplers 453 respectively. 454 be scanned. The low, horizontal component is passed through a vertical low-pass filter 455 and a ver tical high-pass filter 456 to a low, horizontal, low vertical component or H _L V _L signal or to a low horizontal, high vertical component or H _L V _H signal filtered. The two signals H _L V _L and H _L V _H , are then halfway through two sub-samplers 457 respectively. 458 subsampled and to the compression circuit 405 transfer.

The high, horizontal component is through a vertical low-pass filter 459 to a vertical high-pass filter 460 filtered to a high horizontal low vertical component or H _H V _L signal and a high horizontal high vertical component or H _H V _H signal. The two signals, H _H V _L and H _H V _H , then become halfway through two sub-samplers 461 respectively. 462 subsampled and to the compression circuit 405 transfer.

The H _L V _L signal is preferably passed through a first compressor 471 the compression circuit 405 DCT compressed and from a first output 405 as the first data stream transmitted.

Also, the H _L V _H signal is amplified by a second compressor 473 compressed and a second output 464 fed. The H _L V _H signal is passed through a third compressor 463 compressed and the second output 464 fed. The H _H V _H signal is provided by a divider circuit 465 into two video signals, one with high resolution (H _H V _H 1) and one with super high resolution (H _H V _H 2), which are then divided into the second output 464 or a third output 468 be transmitted.

The first video decoder 421 will now be more specific with reference to 31 explained. The first data stream or the D ₁ signal of the first receiver 23 is through an input unit 501 a final cube 502 the first video decoder 421 fed where it is descrambled. The descrambled D ₁ signal is passed through an expander 503 to H _L V _L which then undergoes an aspect ratio change circuit 504 is supplied. Thus, the H _L V _L signal through an output unit 505 in a standard format 500 , a mailbox format 507 , a wide-screen format 508 or a side panel format NTSC signal 509 be delivered. The sample format may be of the non-interlaced or interlaced type and its lines in NTSC mode 525 or doubled up 1050 by double sampling. When the received signal from the digital sender 51 a digital television signal with QPSK mode is, it can also be through the first receiver 23 and the first video decoder 421 be converted into a television picture. The second video decoder 422 will be more detailed with reference to the block diagram of 32 explained. The D ₁ signal of the second receiver 33 is through a first entrance 521 a first expander 522 fed to the data expansion and then to a double scanner 523 where it is scanned 2 ×. The double-sampled signal is passed through a vertical low-pass filter 524 filtered to H _L V _L. Also, the D ₂ signal of the second receiver 33 through a second entrance 530 a divider circuit 531 fed, where it is divided into three components, which then a second 532 , a third 533 or a fourth expander 534 be transferred for data expansion. The three expanded components become 2 × by three double scanners 535 . 536 . 537 sampled and by a vertical high pass 538 , a vertical lowpass 539 or a vertical high-pass filter 540 filtered. Then, H _L V _H from the vertical low-pass filter 524 and H _L V _H from the vertical high-pass filter 538 through an adder 525 summed, by a double scanner 541 sampled and through the horizontal low-pass filter 542 filtered to a horizontal low frequency video signal. H _H V _L from the vertical low pass filter 539 and H _H V _H 1 from the vertical high-pass filter 540 be through an adder 526 summed, sampled by a double sampler and by the horizontal high pass filter 545 to a horizontal video signal higher. Frequency filtered. The two horizontal high and low frequency video signals are then passed through an adder 543 is added to a high definition video signal HD passing through an output unit 546 as a video output 547 , eg in high-definition television format. If desired, a conventional NTSC video output can be played with equal success.

33 is a block diagram of the third video decoder 423 in which the D ₁ and D ₂ signal by a first 521 or a second input 530 a high frequency band video decoder circuit 527 where they are converted into an HD signal in the same way as described above. The D ₃ signal is through a third input 551 a super high frequency band video decoding circuit 552 where it is expanded, descrambled and assembled into a H _H V _H 2 signal. The HD signal of the high frequency band video decoding circuit 527 and the H _H V _H 2 signal of the super high frequency band video decoding circuit 552 be by a summer 553 to a super high resolution television signal or a super high resolution (S-HD) signal, which is then summed through an output unit 554 as a super-resolution video output 555 is delivered.

The effect of multiplexing in the multiplexer 412 the Indian 29 is shown, will be explained in more detail. 34 represents a data allocation in which the three data streams D _1, D _2, D _3, the first, second and third in a period of T six NTSC channel data L1, L2, L3, L4, L5, L6 include six high-definition television channel data M1, M2, M3, M4, M5, M6 and six S-high definition television channel data, H1, H2, H3, H4, H5, H6, respectively contain. In operation, the NTSC or D ₁ signal data L1 to L6 are time-multiplexed by a time-division TDM method according to the period T. In particular, H _L V _L becomes 0, a range 601 assigned to the first channel. Then, a difference data M1 between high-definition television and NTSC or a sum of H _L V _H , H _H V _L and H _H V _H becomes a range 602 assigned for the second channel. Also, a difference data H1 between high definition television and Spuper high definition television or H _H V _H 2 (see 30 ) an area 603 assigned to the first channel.

The selection of the television signal of the first channel will now be described. If it is from the first receptions 23 with a small antenna received with the first video decoder 21 is connected, the first channel signal is converted into a standard or a widescreen NTSC television signal, as in 31 is shown. If it is from the second receiver 33 is received with a middle antenna connected to the second video decoder 422 is connected, the signal is obtained by summing L1 of the first data stream D ₁ corresponding to the area 601 and M1 of the second data stream D ₂ corresponding to the area 602 is converted into a high-definition television signal of the first channel, which is equivalent in the program to the NTSC signal.

If it is from the third receiver 43 with a large antenna received with the third video decoder 423 is connected, the signal by summing L1 and D _1, which is the range 601 is assigned, from M1 and D _2, to the area 602 is assigned, and H1 of _D3, the area of the 603 is converted into a super high-definition television signal of the first channel, which is equivalent in the program the NTSC signal. The other channel signals can be reproduced in the same way.

35 shows another data assignment in which L1 of an NTSC signal of the first channel is a first range 601 assigned. The area 601 Also provided at the front of the first data stream D ₁ is a data S11 including a descramble data for the demodulation data described in the first embodiment. A high-definition television signal of the first channel is transmitted as L1 and M1. M1, which is thus a difference data between NTSC and high-definition television, is the two areas 602 and 611 assigned by D ₂ . If L1 is a compressed NTSC component of 6 Mbps, M1 is twice greater than 12 Mpbs. Therefore, a total of L1 and M1 can work at 18 Mbps with the second receiver 33 and the second video encoder 423 be demodulated. According to current data compression techniques, high-resolution compressed television signals can be reproduced at approximately 15 Mbps. This allows for data mapping, as in 35 is shown to allow simultaneous playback of an NTSC and a high-definition television signal of the first channel. However, this association does not allow a high definition television signal to be carried on a second channel. S21 is a descramble data in the high-definition television signal. A super high definition television signal component of the first channel comprises L1, M1 and H1. The difference data H1 is three areas 603 . 612 . 613 assigned by D ₃ . If the NTSC signal is 6 Mbps, the super HDTV is carried at as high as 36 Mbps. When a compression rate is increased, super high definition television video data of about 2000 scanning lines for reproducing a cinema-size image for commercial use can be transmitted in the same manner.

36 Figure 11 shows another data allocation in which H1 of a super high definition television signal is assigned to six time ranges. If a compressed NTSC signal is 6 Mbps, this allocation can carry nine times more than 54 Mbps of D ₃ data. Accordingly, super high definition television data of higher picture quality can be transmitted.

The The above data mapping uses one of two horizontal and one vertical, polarization planes of a transmission wave. If the horizontal and the vertical polarization plane are used the frequency usage is doubled. This will be explained below.

49 shows a data assignment in which D _V1 and D _{H1 is} a vertical or a horizontal polarization signal of the first data stream, D _V2 and D _{H2 is} a vertical and a horizontal polarization signal of the second data stream and D _V3 and D _{H3 is} a vertical and horizontal Polaristationssignal the third data stream is. The vertical polarization signal D _{V1 of} the first data stream carries a low frequency band or NTSC television data and the horizontal polarization signal D _H1 carries a high frequency band or high definition television data. If the first recipient 23 equipped with a vertical polarization antenna, it can only reproduce the NTSC signal. If the first recipient 23 equipped with an antenna for the horizontally and vertically polarized wave, it can reproduce the high-definition television signal by summing L1 and M1. More precisely, the first receiver 23 a compatibility between NTSC and high-definition television when using a special kind of antenna.

50 illustrates a time division multiple access method in which each burst of data 721 front of sync data 731 and map data 471 is accompanied. Also, data transfer block synchronization data 720 provided in front of a frame. Same channels are assigned to the same time slots. For example, a first timeslot carries 750 NTSC, high-definition television and super high-definition television data of the first channel at the same time. The six timeslots 750 . 750a . 750b . 750c . 750d . 750e are arranged independently of each other. Therefore, each station can offer NTSC, HDTV, and / or super HDTV services independently of the other stations by selecting a particular channel of the time slots. Also, the first receiver 23 play an NTSC signal when equipped with a horizontal polarization antenna and NTSC and high resolution television signals when equipped with a compatible polarization antenna. In this regard, the second receiver 33 Play a super HDTV signal at a lower resolution while the third receiver 43 can play a full super HDTV signal. According to the third embodiment, a compatible signal transmission system is constructed. It is understood that the data allocation is not limited to the time division multiple access burst format mode used in 50 and another method, such as time division multiplexing of continuous signals as shown in FIG 49 shown is used with equal success. Also allows a data mapping that in 51 It is shown that a high-definition television signal with high resolution is reproduced.

As As stated above, the compatible digital high-definition television television signal transmission system the third embodiment three television services, super high-definition television, high-definition television and conventional NTSC, offer at the same time. Furthermore, a video signal, that has been received by a commercial station or a cinema is to be electronized.

The modified QAM of the embodiments is now called SRQAM and its error rate is being investigated.

First, the error rate at 16 SRQAM is calculated. 99 shows a vector diagram of 16 SRQAM signal points. As is apparent from the first quadrant, the 16 signal points of the standard are 16 QAM inclusive 83a . 83b . 84a . 84b allocated at equal intervals of 2δ.

The signal point 83a is spaced from the I-axis and the Q-axis of coordinates δ. It is now assumed that n is a shift value of the 16 SRQAM. At the 16 SRQAM is the signal point 83a the 16 SRQAM to a signal point 83 shifted, where the distance from each axis is nδ. The shift value n is thus expressed as
0 <n <3.

The other signal points 84a and 86a are also to two points 84 respectively. 86 postponed.

If the error rate of the first data stream is P _e1 , it is obtained from:

Also, the error rate P _{e2 of} the second data stream is obtained from:

The error rate of the 36 or 32 SRQAM is calculated. 100 Figure 12 is a vector diagram of a 36 SRQAM signal in which the distance between any two 36 QAM signal points 26 is.

The signal point 83a the 36 QAM is δ spaced from each axis of the coordinate. It is now assumed that n is a shift value of the 16 SRQAM. At the 36 SRQAM the signal point becomes 83a to a signal point 83 shifted, where the distance from each axis is nδ. Similarly, the nine 36 QAM signal points in the first quadrant become points 83 . 84 . 85 . 86 . 97 . 98 . 99 . 100 respectively. 101 postponed. If a signal point group 90 representing the nine signal points considered to be a single signal point, the error rate P _e1 in the reproduction of only the first data stream D ₁ with a modified QPSK receiver and the error rate P _e2 in the reproduction of the second data stream D ₂ after the distinction of nine signal points of the group 90 each received from:

101 shows the relationship between the error rate P _e and C / N rate in the transmission, where the curve 900 represents a conventional and an unaltered 32 QAM signal. The straight line 905 represents a signal with an error rate of 10 ^-1.5 . The curve 901 represents a 32 SRQAM signal with D ₁ level of the present invention at the shift value n of 1.5. As shown, the C / N rate of the 32 SRQAM signal is 5 dB lower at the error rate of 10 ^-1.5 than that of the conventional 32 QAM. That is, the present invention allows a D ₁ signal to be reproduced at a given error rate when its C / N rate is relatively low.

The curve 902a represents an SRQAM signal with D ₂ level at n = 1.5, which can even be reproduced at the error rate of 10 ^-1.5 , only if its C / N rate is 2.5 dB higher than that of the conventional 32 QAM Curve 900 is. Also set the curves 901b and 902b SRQAM signals from D ₁ and D ₂ at n = 2.0. The curve 902c represents a D ₂ SRQAM signal at n = 2.5. It is apparent that the C / N rate of the SRQAM signal at the error rate of 10 ^{-1.5 is} 5dB, 8dB and 10dB higher at n = 1.5, 2 , 0 and 2.5, respectively, with respect to the D ₁ level and 2.5 dB lower at the D ₂ level than that of a conventional 32 QAM signal.

In 103 For example, the C / N rate of the first and second data streams D ₁ , D _{2 of} the 32 SRQAM signal needed to maintain a constant error rate against a change in shift n is shown. As is apparent, when the shift n is more than 0.8, a clear difference between two C / N rates of their respective D ₁ and D ₂ levels is developed, so that the multi-level signal transmission, namely, the first and second data , can be executed successfully. In short, n> 0.85 is essential for multi-level data transmission of the 32 SRQAM signal of the present invention.

102 shows the relationship between the S / N rate and the error rate for 16 SRQAM signals. The curve 900 represents a standard 16 QAM signal. The curve 901 . 901b . 901c are 16 SRQAM signals with a D ₁ level or the first data stream at n = 1,2, 1,5 and 1,8 respectively. The curve 902a . 902b . 902c are 16 SRQAM signals with a D ₂ level or the second data stream at n = 1,2, 1,5 and 1,8, respectively.

The S / N rate of the first and second data streams D ₁ , D _{2 of} a 16 SRQAM signal is in 104 which is needed to maintain a constant error rate against a change in displacement n. As is apparent, when the shift n is more than 0.9 (n> 0.9), the multi-level data transfer of the 16 SRQAM signal is executed.

An example of the propagation of SRQAM signals of the present invention will now be described for use with a digital terrestrial television service. 105 shows the relationship between the signal level and the distance between a transmitter antenna and a receiver antenna in the terrestrial television service. The curve 911 represents a transmitted signal from the transmitter antenna which is 1250 feet high. It is assumed that the error rate, which is essential for the reproduction of an applicable digital television ^signal, is 10 ^-1.5 . The hatched area 912 represents a noise interruption. The point 910 represents a signal reception limit of a conventional 32 QAM signal at S / N = 15 dB, where the distance L is 60 miles and a high-definition digital television signal can at most be picked up.

The S / N rate varies 5 dB at a worse reception condition like bad weather.

If a change at the relevant conditions, e.g. Weather weakening S / N rate will the reception of a high-definition television signal hardly guaranteed. Also affect geographic conditions strong the propagation of signals, and a decrease of at least approximately 10 dB will be inevitable. Therefore, a successful signal reception never guaranteed within 60 miles, and in addition spreads a digital signal is harder than an analog signal. you understands that the Coverage area of a conventional, digital television service is less dependent.

In the case of the 32 SRQAM signal of the present invention, a three-level signal transmission system is formed as shown in FIGS 133 and 137 is shown. This allows a resolution of an NTSC signal of MPEG level, which is carried on the 1-1 data stream D _1-1, a medium resolution TV data of eg NTSC system, on the 1-2 data stream D _{1 2} data stream D _1-2 and a high frequency component of HDTV data carried on the second data stream D ₂ . Accordingly, the coverage area of the SRQAM Si 1-2 data stream becomes gnals raised to a point 910h by 70 miles, while the second data stream within a point 910b 55 miles remains as it is in 105 is shown. 106 FIG. 12 illustrates a computer simulation result of the coverage area of the 32 SRQAM signal of the present invention, similar to FIG 53 is, but explained more in detail. It shows the areas set 708 . 703c . 703a . 703b . 712 a conventional 32 QAM reception area, a reception area for a 1-1 data level D _1-1, a reception area for a 1-2 data level D _1-2 , a reception area for a second data level D _1, and a coverage area of an adjacent analog television station, respectively The conventional 32 QAM signal data used in this drawing are based on conventionally disclosed data.

at a usual one 32 QAM signal can be the coverage area with a radius of 60 Miles are theoretically produced. The signal level will however attenuated by geographical and weather conditions and especially near the border of the fueling area.

When the television component is in the low frequency band of the MPEG1 degree on the data of the 1-1 level D _1-1 and the television component in the middle frequency band of the NTSC degree on the data of the 1-2 level D _1-2 and the television component in the high frequency band of the HDTV are carried on the data of the second level D ₂ , the coverage area of the 32 SRQAM signal of the present invention within the radius of 10 miles for receiving a medium-resolution resolution EDTV signal and 18 miles to receive an LDTV A low-level resolution signal, although reduced by 5 miles for receiving a high-definition resolution HDTV signal, as it does in 106 is shown. 107 shows a coverage area in the case of a shift factor n or s = 1.8. 135 shows the coverage area of 107 in terms of area.

Especially can be a medium resolution component of a digital television signal of the SRQAM mode of the present invention succeeds in one unfavorable Supply area or shadow area are received where one conventional TV signal in the middle frequency band barely spread and due the obstacle se weakened is. At least within the predetermined coverage area Can the NTSC TV signal of SRQAM mode from any conventional TV receiver be received. Because the shadow or signal attenuating area, the through building structures and other obstacles or by interference from an adjacent, analog television signal is developed, or in a low-lying Land is generated, is reduced to a minimum, the number is the television viewer or subscriber increases.

Also can the high-definition television service appreciated by only a few observers who can afford a costly high-definition television and display device over the usual System to have. The system of the present invention allows that a common one NTSC, PAL or SECAM receiver a medium resolution component digital high-definition television signal using an additional, digital tuner receives. The biggest part The television viewer can therefore use the service at lesser Costs enjoy and their number is increased. This will encourage the television business and an additional, generate social advantage.

Of further is the range with signal reception with medium resolution or NTSC television service according to the present Invention at about 36% increased at n = 2.5, compared to the conventional one System. If the coverage area and thus the number of television Viewers increased will, the television business enjoys an increasing profit. This reduces a risk in the development of a new digital television Business, thus being encouraged to be put into practice.

107 FIG. 12 shows the coverage area of a 32 SRQAM signal of the present invention, ensuring the same effect at n = 1.8. Two service areas 703, a . 703b of the D ₁ and D ₂ signals, respectively, may be determined to expand for optimum signal propagation by varying the displacement n, taking into account a profile of the high definition television and NTSC receiver distribution or geographical features. Accordingly, television viewers serve the service and a service station enjoys maximum viewership.

This advantage is given if:
n> 1.0

Therefore, when the 32 SRQAM signal is selected, the displacement n is determined to be:
1 <n <5

Also, when the 16 SRQAM signal is used, n determines:
1 <n <3

In the terrestrial television service with a signal in SRQAM mode in which the first and second data levels are generated by shifting corresponding signal points, such as it in 99 and 100 is shown, the advantage of the present invention results when the displacement n is greater than 1.0 for a 16, 32 or 64 SRQAM signal.

In the above embodiments become the components of a video signal in low and high Frequency band as the first and second data streams. The transferred However, the signal can be an audio signal. In this case, the low-frequency or low-resolution components of an audio signal as the first data stream and the high-frequency or high-resolution components an audio signal are transmitted as the second data stream. Corresponding Is it possible, the high S / N proportion in high sound quality and the low level portion S / N in low sound quality to recieve. This can be useful in PCM broadcasting, radio, portable Telephone and the like can be used. In this case, the broadcast transmission area or the communication distance is increased compared to the usual Systems.

Furthermore, the third embodiment may include a time division multiplexing (TDM) system, as disclosed in US Pat 133 is shown. The use of the TDM makes it possible to increase the number of auxiliary channels. An ECC encoder 743a and an ECC encoder 743b , which are provided in two subchannels, distinguish ECC code gains to make a difference between thresholds of these two subchannels. Thereby, an increase of the channel number of the multi-level signal transmission can be achieved. In this case it is also possible to use two trellis encoders 743a . 743b to create, as in 137 and to differentiate their code gains. The explanation of this block diagram is substantially identical to that of the block diagram of FIG 131 showing the sixth embodiment of the present invention and therefore will not be described here.

In a simulation of 106 For example, a 5dB difference of coding gain is provided between the 1-1 auxiliary channel D _1-1 and the 1-2 auxiliary channel D _1-2 .

One SROAM is the system that uses a C-CDM (Coordinate Code Division Multiplex) of the present invention applies to a rectangular QAM. A C-CDM, which is a multiplexing method independent of TDM or FDM auxiliary channels by dividing a constellation code according to a code receive. An increase the number of codes will increase the transmission capacity which is not achieved by TDM or FDM alone, where a nearly perfect compatibility with a conventional one Communication device is maintained. C-CDM can therefore be excellent Effects.

Although the above embodiment combines C-CDM and TDM, it is also possible to combine C-CDM with FDM (Frequency Division Multiplex) to obtain a similar modulation effect of thresholds. Such a system can be used for television broadcast, and 108 shows a frequency distribution of a television signal. A spectrum 725 represents a frequency distribution of a conventional analog, eg NTSC, television signal. The largest signal is a video carrier 722 , A color carrier 723 and a sound carrier 724 are not that big. There is known a method in which an FDM is used for dividing a digital television signal into two frequencies. In this case, the carrier is in a first carrier 726 and a second carrier 727 divided to a first signal 720 or a second signal 721 to ask. Interference can be reduced by first and second carriers 726 . 727 sufficiently removed from the video carrier 722 to be placed. The first signal 720 serves to transmit a low-resolution television signal at a high output level, while the second signal 721 serves to transmit a high-definition television signal at a low output level. Consequently, the multi-level signal transmission using an FDM can be realized without being hindered by interference.

134 shows an example of a conventional method using a 32-QAM system. Since the auxiliary channel A has a larger output than the auxiliary channel B, a threshold for the auxiliary channel A, ie a threshold 1, 4-5dB can be set smaller than a threshold for the auxiliary channel B, ie a threshold 2. Accordingly, two-level television transmission be realized with a threshold difference of 4-5 dB. In this case, however, a large reduction in the signal reception amount will occur when the level of the reception signal falls below the threshold 2, since the second signal 721a , which has a large information content, as hatched in the drawing, can not be received in such a case. and only the first signal 720a that has a small amount of information is received. Consequently, image quality brought by the second level will be extremely worse.

However, the present invention solves this problem. According to the present invention, the first signal is 720 is given by a 32 SRQAM mode, which is obtained by C-CDM modulation, so that the auxiliary channel A is divided into two auxiliary channels 1 of A and 2 of A. The newly added auxiliary channel 1 of A, which has the lowest threshold, carries a low-resolution component. The second signal 721 is also given by a 32 SRQAM mode, and a threshold for the auxiliary channel 1 of B is equated with the threshold 2.

In this arrangement, the range in which a transmitted signal is not received when the signal level falls below the threshold 2 is limited to a hatched portion of the second signal 721a in 108 reduced. Since the auxiliary channel 1 of B and the auxiliary channel A are receivable, the transmission amount is not reduced so much overall. Accordingly, better picture quality is also reproduced in the second level at the threshold level signal 2. By transmitting a normal-resolution component in an auxiliary channel, it becomes possible to increase the number of multiple levels and to increase a low-resolution coverage area. This low-threshold sub-channel is used to transmit important information such as audio information, synchronization information, heads of corresponding data, as this information carried in this low-threshold sub-channel can be safely received. Therefore, stable reception is feasible. If an auxiliary channel is new in the second signal 721 is added in the same way, the level number of the multi-level transmission in the service area can be increased. In the event that an HDTV signal 1050 May have a new coverage area, equivalent to 775 Lines are created in addition to 525 lines. Accordingly, the combination of the FDM and the C-CDM realizes an increase in the coverage area. Although the above embodiment divides an auxiliary channel into two auxiliary channels, it need not be said that it will be advantageous to place it in three or more auxiliary channels. to divide.

Next, a method for avoiding noise by combining TDM and C-CDM will be explained. As in 109 is shown, an analog remote signal includes a horizontal retrace line component 732 and a video signal component 731 one. This method uses a low signal level of the horizontal retrace line component 732 and not displaying a disturbance on an image plane during that period of time. By synchronizing a digital television signal with an analog television signal, horizontal retrace line synchronization slots can be provided 733 . 733a of the horizontal return line component 732 for transmitting an important signal, eg a synchronization signal, or numerous data at a high output level. This makes it possible to increase the amount of data or the output level without increasing noise. The similar effect is expected, even if vertical retrace line synchronization slots 737 . 737a synchronous with vertical return line components 735 . 735a are provided.

110 shows a principle of C-CDM. In addition, shows 111 a code mapping of the C-CDM equivalent to an extended 16 QAM. 112 shows a code mapping of the C-CDM equivalent to an extended 36 QAM. As in the 110 and 111 is a 256 QAM signal in four levels 740a . 740 . 740c . 740d divided, which have 4, 16, 64 or 256 segments. A signal codeword 742d of the 256 QAM at the fourth level 740d is "11111111" of 8 bits.This is in four codewords 741a . 741 . 741c and 741d divided by 2 bits, ie "11", "11", "11", "11", which then signal point ranges 742a . 742 . 742c . 742d of first, second, third and fourth levels, respectively 740a . 740 . 740c respectively. 740d assigned. As a result, auxiliary channels 1, 2, 3, 4 of 2 bits are created. This is called C-CDM (Constellation Code Division Multiplex). 111 shows a detailed code assignment of the C-CDM equivalent to extended 16 QAM, and 112 shows a detailed code mapping of the C-CDM equivalent to extended 36 QAM. Since the C-CDM is an independent multiplexing system, it can be combined with the conventional FDM (Frequency Division Multiplexing) or TDM (Time Division Multiplexing) to further increase the number of auxiliary channels. In this way, the C-CDM system implements a new multiplex system. Although the C-CDM has been explained using a rectangular QAM, other modulation systems with signal points, eg QAM PSK, ASK and even FSK, if frequency ranges are considered signal points, can be used for this multiplex in the same way.

Embodiment 4

A fourth embodiment The present invention is described with reference to the relevant Drawings described.

37 Fig. 10 illustrates the entire arrangement of a signal transmission system of the fourth embodiment; which is arranged for a terrestrial service and is similar in construction and effect to that of the third embodiment, which is incorporated herein by reference 29 is shown. The difference is that the transmitter antenna through a terrestrial antenna 6a is replaced and the receiver antennas 22 . 32 . 42 by also three terrestrial antennas 22a . 32a . 42a are replaced. The effect of the system is identical to the third embodiment and will not be explained any more. The terrestrial television service, unlike a satellite service, depends heavily on the distance between the transmitter antenna 6a and the receiver antenna 22a . 32a . 42a from. When a receiver is far away from the transmitter, the level of a received signal is low. In particular, a general multi-level QAM signal can hardly be demodulated by the receiver, thus producing no television program.

The signal transmission system of the present invention allows the first receiver 23 that with the antenna 22a equipped, which is located at a great distance, as it is in 37 is shown receiving a modified 16 or 64 QAM signal and demodulating a QPSK mode of the first data stream or the D ₁ component of the received signal into an NTSC video signal so that a medium resolution television program picture may even be displayed when the level of the received signal is relatively low.

Also, there is the second receiver 33 with the antenna 32a at a medium distance from the antenna 6a and thus may receive and demodulate the first and second data streams or the D ₁ and D ₂ components of the modified 16 or 64 QAM signal into a high definition television video signal which, in turn, generates a high definition television program image.

The third receiver 43 with the antenna 42a is located at close range and can receive and demodulate the first, second, and third data streams, or the D ₁ , D _2, and D ₃ components of the modified 16 or 64 QAM signal into a super high definition television video signal, which in turn carries a super high definition television picture the same quality as a usual motion picture film produced.

The allocation of frequencies is determined in the same way as in the time division multiplexing, which in the 34 . 35 and 36 is shown. As in 34 when the frequencies are assigned to the first to sixth channels, L1 of the D ₁ component carries NTSC data of the first channel, M1 of the D ₂ component carries high definition television difference data of the first channel and H1 of the D ₃ component carries super HDTV difference data of the first channel. Accordingly, NTSC, HDTV and super HDTV data can all be carried on the same channel. If D ₂ and D _{3 of} the other channels are used, as in the 35 and 36 As shown, more data from high definition television or super high definition television may be transmitted for display at a higher resolution.

As will be understood, the system allows three different but compatible digital television signals to be carried on a single channel or the D ₂ and D ₃ ranges of the other channels. Also, the medium resolution television image data may be received by each channel in a wider coverage area in accordance with the present invention.

A Variety of terrestrial, digital television systems that use a 16 QAM High-resolution television signal with 16 MHz bandwidth have been proposed. These are however not compatible with the existing NTSC system and thus need with a simultaneous transmission technique for transmission of NTSC signals from the same program on a different channel become. Also, such a common 16 QAM signal limits the coverage area. The terrestrial broadcast system of the present invention allows the existence Receiver, which is in a relatively large Distance is successful, a medium resolution television signal without Use of an additional Establishment of an additional one Channel receives.

52 shows a fault area of the service area 702 a conventional, terrestrial, high-definition digital television station 701 , As shown, the coverage area intersects 702 the conventional high-definition television station 701 with the supply area 712 an adjacent analog TV station 711 , At the cutting area 713 becomes a high definition television signal due to signal interference from the analog television station 711 attenuated and thus received with less consistency.

53 Fig. 10 shows a noise region associated with the multi-level signal transmission system of the present invention. The system has a low energy usage compared to the conventional system and its service area 703 for high-definition television signal propagation is smaller than the area 702 of the conventional system. In contrast, the supply area 704 for digital NTSC or medium resolution television signal propagation greater than the conventional range 702 , The level of signal interference between a digital TV station 701 of the system with an adjacent, analog television station 711 In addition, it is equivalent to a conventional digital television station, as in 52 is shown.

In the coverage area of the digital TV station 701 There are three interference areas caused by signal interference from the analog TV station 711 be developed. High-definition television and NTSC signals can barely be in the first range 705 be received. An NTSC signal, although severely disturbed, may be at an equal level in the second range 706 received, which is indicated by the hatching to the bottom left. The NTSC signal is carried on the first data stream, which can be reproduced at a relatively low S / N rate, and is thus minimally affected when the S / N rate is due to signal interference from the analog television station 711 is weakened.

In the third area 707 Also indicated by hatching to the lower right, a high-definition television signal may also be received when a signal disturbance is missing, while the NTSC signal can be continuously received at a low level.

Accordingly, the entire area with signal reception of the system increases, though the coverage area of high-definition television signals something smaller than that of the conventional one Systems will. Also can in the signal attenuation areas, the by fault be generated with a neighboring, analog television station, Signals with NTSC level of high-definition television program successful compared to the conventional one System where no high-definition television program in the entire area is seen. The system of the present invention reduces the size of the signal attenuator Areas, and when the energy of the signal transmission at a transmitter or transponder station increases, it may be the high-definition television signal coverage area to the same size as that conventional Expand system. Also can signals with NTSC level of a television program more or less in one distant area are received, where by the conventional system no reception, or in a signal interference area, caused by an adjacent, analog television station becomes.

Although the embodiment uses a two-level signal transmission method, a three-level method as described in U.S. Pat 78 shown to be used with the same success. When a high-definition television signal is divided into three high-resolution television screens, NTSC and NTSC with low resolution, the service areas included in 53 are increased from two levels to three levels where the signal propagation is expanded radially and outwardly. Also, low resolution NTSC signals may have an acceptable level in the first signal interference region 705 where NTSC signals are hardly received in the two-level system. It is understood that the signal interference is also included from a digital television station to an analog television station.

The description will now be continued, provided that no digital television station should cause a signal interference with any adjacent analog television station. According to a novel system considered in the USA, unused channels of the existing transmission channels are used for high-definition television, and thus digital signals do not have to interfere with analog signals. For this purpose, the transmission level of a digital signal must be reduced lower than that in 53 is shown. When the digital signal is one of the conventional 16 QAM or QPSK mode, its high definition television coverage area becomes 708 reduced because the signal interference area 713 which is characterized by crosshatching, is pretty big, as it is in 54 is shown. This results in a smaller number of viewers and sponsors, making such a digital system very difficult to operate as a profit-oriented business.

55 , shows a similar result according to the system of the present invention. As it is apparent, the high-definition television signal reception area is 703 a little smaller than the same area 708 of the conventional system. However, the reception area becomes 704 for the NTSC television signal or the lower resolution compared to the conventional system. The hatched area represents an area where the NTSC level signal of a program can be received while the high-definition television signal thereof is hardly received. In the first fault area 705 High-definition TV and NTSC signals may be due to signal interference from an analogue station 711 not received.

When the level of the signals is the same, the multi-level transmission system of the present invention provides a smaller high-definition television service area and a larger NTSC service area for receiving a high-definition television program at an NTSC signal level. Accordingly, the total broadcasting area of each station is increased and more viewers can enjoy the TV television service. Furthermore, a high definition television / NTSC compliant television company can be operated with economic advantages and durability. It is also envisaged that the level of a transmission signal will be increased if the control for attenuating signal interference with adjacent analog television stations is reduced in accordance with a sharp increase in the number of home-use digital receivers. Therefore, the coverage area of high-definition television signals is increased, and in this regard, the two different areas for receiving high-definition television digital television signal levels / NTSC and NTSC, respectively, can be obtained 55 are set proportionally by the signal point distance in the first and / or second. Data stream is changed. When the first data stream carries information about the signal point distance, a multi-level signal can be received with more security.

56 adjusts the signal interference two digital television stations in which an adjacent television station 701 also provides a digital television service compared to an analogue station in 52 , As the level of a transmission signal becomes large, the reception range becomes 703 for the high-definition television service or a television signal of high resolution up to an extent equal to the transmission range 702 an analog television system.

In the cutting area 714 between two coverage areas of their respective stations, the received signal can not be reproduced to a high resolution television picture level using a conventional directional antenna because of the signal interference, but up to an NTSC image level with a particular directional antenna directed towards a desired television station. When a high-directional antenna is used, the received signal from a destination station is reproduced as a high-definition television picture. The reception area 704 for low resolution signals becomes stronger than the coverage area 702 of the analogue television system, and several cutting areas 715 . 716 passing through the two reception areas 704 and 704a their respective digital television stations 701 and 701 for low resolution signals, allow the signal received by the antenna, which is aligned with one of the two stations, to be reproduced as an NTSC level picture.

Of the HDTV service area the multi-level signal transmission system of The present invention itself is greatly increased if the applicable Signal restriction rules at development conclusion of a future, digital TV service withdrawn become.

Currently delivers the system of the present invention also provides a wide, high definition television signal reception area as with the conventional one System and allows in particular, that his signal transmission at an NTSC level in a more distant or intersecting area is reproduced where television signals of the conventional system hardly receive become. Accordingly, become signal attenuating or shadow areas in the broadcast area minimized.

Embodiment 5

A fifth embodiment of the present invention is in the amplitude modulation or the ASK method. 57 illustrates the assignment of signal points of a 4-level ASK signal according to the fifth embodiment, in which four signal points with 721 . 722 . 723 and 724 are designated. The four-level transmission allows 2-bit data to be transmitted in each cycle period. It is assumed that the four signal points 721 . 722 . 723 . 724 each two-bit pattern 00, 01, 10, 11 represent.

For simplification of the four-level signal transmission of the embodiment, the two signal points become 721 . 722 as first signal point group 725 and the other two 7 23 . 724 be as second signal point group 726 designated. The distance between two signal point groups 725 and 726 is then determined to be wider than that between any two adjacent signal points. More specifically, the distance Lo becomes between the two signals 722 and 723 farther than the distance L between two neighboring points 721 and 722 or 723 and 724 arranged. This is expressed as:
Lo> L

Therefore is the multi-level signal transmission system the embodiment Underlying Lo> C. The embodiment is not on Lo> L limited and L = La becomes temporary or permanently dependent on the requirements of construction, operation and adjustment used.

The two signal point groups are assigned one-bit patterns of the first data stream D ₁ , as shown in FIG 59 (a) is shown. More specifically, a bit 0 of the binary system of the first signal point group 725 assigned and another bit 1 of the second signal point group 726 , Then, a one-bit pattern of the second data stream D ₁ is assigned to each signal point. For example, the two signal points 721 . 723 D ₂ = 0 assigned and the other two signal points 722 and 724 D ₂ = 1 is assigned. Those are thus expressed by two bits per drawing.

The multi-level signal transmission system of the present invention may be executed in an ASK mode using the above signal point assignment. The system of the present invention operates in the same manner as a conventional one with the same signal point spacing technique when the signal to noise ratio or the S / N rate is high. When the S / N rate becomes low and data can not be reproduced by the conventional technique, the present system ensures the reproduction of the first data stream D ₁ but not the second data stream D ₂ . More specifically, the condition is low S / N in 60 shown. The transmitted signal points become the areas by a Gaussian distribution 712a . 722a . 723a . 724a shifted on the receiver side due to noise and transmission distortion. Therefore, the distinction between two signals 721 and 722 or 723 and 724 , executed. In other words, the error rate in the second data stream D ₂ elevated. It out 60 Obviously, the two signal points become 721 . 722 without further ado from the other two signal points 723 . 724 distinguished. The distinction between the two signal point groups 725 and 726 can thus be carried out easily. As a result, the first data stream D _{1 is} reproduced at a lower error rate.

Accordingly, the two different level data D ₁ and D ₂ can be transmitted simultaneously. In particular, the first and second data streams D ₁ and D _{2 of} a given signal transmitted by the multilevel transmission system can be reproduced in the area where the S / N rate is high, and the first data stream D ₁ can only be in the area where the S / N rate is low.

61 is a block diagram of a transmitter 741 in which the input unit 742 a first data stream input 743 and a second data stream input 744 includes. A carrier wave from a carrier generator 64 is by a multiplier 746 amplitude modulated using an input signal through a processor 745 from the input unit 743 is supplied. The modulated signal is then passed through a filter 747 band limited to an ASK signal of a VSB mode, for example, then from an output unit 748 is delivered.

The waveform of the ASK signal after filtering is now examined. 62 (a) shows a frequency spectrum of the ASK modulated signal, in which two sidebands are provided on both sides of the carrier frequency band. One of the two sidebands goes through the filter 477 ruled out a signal 747 to produce, which contains a carrier component, as in 62 (b) is shown. The signal 749 is a VSB signal, and when the modulation frequency band is fo, it is transmitted in a frequency band of about fo / 2. Therefore, the frequency utilization becomes large. Using the transfer in VSB mode, the ASK signal can draw from two bits per drawing, as shown in 60 is thus shown to carry in the frequency band an amount of data equal to that of a 16 QAM mode at four bits per character.

63 is a block diagram of a receiver 751 in which one through a terrestrial antenna 32a received input signal through an input unit 752 to a mixer 753 will ask where it is with a signal from a variable oscillator 754 which is controlled by the channel selection, is mixed to a signal having a lower middle frequency. The signal from the mixer 753 is then from a detection device 755 detected and by a low-pass filter LPF 756 filtered to a baseband signal leading to a discriminator / regenerator circuit 757 is transmitted. The discriminator / recovery circuit 757 returns two data streams, a first D ₁ and a second D ₂ from the baseband signal, and transmits them further through a first one 758 or a second data stream output 759 ,

The transmission of a television signal using such a transmitter and receiver will be explained. 64 is a block diagram of a video signal transmitter 774 in which a television signal of high resolution, for example, a high-definition television signal, by an input unit 403 a divider circuit 404 a first video encoder 401 where it is divided into four high / low frequency television signal components, for example H _L V _L , H _L V _H , H _H V _L and H _H V _H. This effect is identical to the third embodiment described previously with reference to FIG 30 has been described, and will be explained in more detail. The four separate television signals are each by a compressor 405 is encoded using a known coding technique with a variable length DPCMDCT code which is commonly used, eg in MPEG. Incidentally, the motion compensation of the signal at the input unit 403 executed. The compressed signals are passed through a summer 771 to two, a first and a second, data streams D ₁ , D ₂ summed. The video signal component of low frequency or H _L V _L signal is included in the first data stream D ₁ . The two data stream signals D ₁ , D ₂ then become a first 744 and a second data stream input 747 a transmitter unit 741 where they are amplitude modulated and summed into an ASK signal of, for example, VSB mode broadcast by a terrestrial antenna for a television service.

65 Figure 11 is a block diagram of a television receiver for such a digital television system. A digital television signal coming from a terrestrial antenna 32a has been received, is an input 752 a receiver unit 751 in the television receiver 781 fed. The signal then becomes a detection / demodulation circuit 760 where a desired channel signal is selected and demodulated into two, a first and a second, data streams D _1, D ₂ , which then a first channel 758 or a second data stream output 759 be supplied. The effect in the receiver unit 751 is similar to that previously described and will not be explained in detail. The two data streams D _1, D ₂ become a divider unit 776 sent, in the D ₁ by a divider 777 is divided into two components; one or the compressed H _L V _L becomes a first input 521 a second video decoder 422 transferred, and the other is a summer 778 fed to where they are before transferring to a second input 531 the second video decoder 422 is summed to D ₂ . The compressed H _L V _L is then from the first input 521 to a first expander 523 sent, where it is expanded to H _L V _{L of} the original length, which then becomes a video mixer 458 and an aspect ratio changing circuit 779 is transmitted. If the input television signal is a high-definition television signal, H _L V _{L represents} an NTSC signal for a wide screen. If the same is an NTSC signal, H _L V _{L represents} a lower resolution video signal, eg, MPEG1, as an NTSC level ,

The input television signal of the embodiment is a high definition television signal, and H _L V _L becomes an NTSC signal for wide screen. If the aspect ratio of an available display is 16: 9, H _L V _{L will} pass directly through an output unit as a 16: 9 video output 426 delivered. When the display has an aspect ratio of 4: 3, H _L V _{L is changed} by the aspect ratio changing circuit 779 is moved to the format of a mailbox or a page board and is then viewed as a video output 425 with an appropriate format from the source unit 780 delivered.

The second data stream D ₂ coming from the second data stream output 759 the summer 778 has been supplied to the output of the divider 777 summed to a sum signal, which then the second input 531 the second video decoder 422 is supplied. The sum signal further becomes a divider circuit 531 where it is divided into three compressed formats of H _L V _H , H _H V _L and H _H V _H. The three compressed signals are then a second 535 , a third 536 or a fourth expander 537 to be converted by expansion to H _L V _H , H _H V _L and H _H V _{H of} the original length. The three signals are passed through the video mixer with H _L V _L 548 is summed up into a composite high-definition television signal passing through an output 546 the second video decoder of the output unit 780 is supplied. Finally, the high-definition television signal from the output unit 780 as a high-definition television video signal 427 delivered.

The output unit 780 is arranged to have an error rate in the second data stream of the second data stream output 759 by an error rate determination device 782 and when the error rate is high, H _L V _{L of} the low-resolution video data is systematically supplied.

Accordingly, the multi-level signal transmission system becomes feasible for transmission and reception of digital television signals. For example, when a transmitter station for a television signal is near, the first and second data streams of a received signal can be successfully reproduced to show a high-definition television quality picture. When the transmitter station is far away, the first data stream can be played back to a H _L V _L which is converted to a low resolution television picture. Therefore, any television program is received in a wider area and displayed with an image quality ranging from a high-definition television to NTSC level.

66 Fig. 10 is a block diagram showing another arrangement of the television receiver. As shown, the receiver unit contains 751 only a first data stream output 768 , and thus the processing of the second data stream or high-definition television data is not necessary, so that the overall construction can be minimized. It's a good idea to have the first video decoder 421 who in 31 is shown as having a video decoder of the receiver. Accordingly, an image with NTSC level is reproduced. The receiver is manufactured at a much lower cost because it does not have the ability to receive any high-definition television signal and is widely accepted by the market. In short, the receiver can be used as a matched tuner for receiving a digital television signal without. to request a change to the existing television system including an ad.

The television receiver 781 may have a further embodiment, which in 67 and serves as a satellite television receiver for demodulating PSK signals and a terrestrial television receiver for demodulating ASK signals. In use is a PSK signal coming from a satellite antenna 32 is received by a mixer 786 with a signal from an oscillator 787 mixed to a low frequency signal, then through an input unit 34 a mixer 753 which is similar to that in 63 is shown. The low frequency signal of the PSK or QAM mode in a given channel of the television satellite system becomes a modulator 35 where two data streams D ₁ and D ₂ are reproduced from the signal. D ₁ and D ₂ are separated by a divider 788 to a second video decoder 422 sent, where they are converted into a video signal, then from an output unit 780 is delivered. Also, a digital or analog, terrestrial television signal is transmitted by a terrestrial antenna 32a received by an input unit 752 the mixer 753 where a desired channel is selected in the same way as it is in 63 has been described, and as a basis band signal low frequency is detected. The signal of analog form is directly for demodulation to the demodulator 35 cleverly. The signal of digital form then becomes an discriminator / reproduction circuit 757 where two data streams D ₁ and D ₂ are reproduced from the signal. D ₁ and D ₂ are passed through the second video decoder 422 converted into a video signal, which is then delivered on. An analog television satellite signal becomes a video demodulator 788 where it is AM-demodulated to an analog video signal, then from the output unit 780 is delivered. It is understood that the mixer 753 of the television receiver 781 who in 67 shown is compatible between two television services, a satellite and a terrestrial service is formed. Also, a receiver circuit having a detection device 755 and a low pass filter TPF 756 for AM demodulation of an analog signal, compatible with a digital ASK signal of the terrestrial television service. The main part in 67 shown embodiment is designed for compatible use, so that the circuit construction is minimized.

According to the embodiment, a 4-level ASK signal is divided into two level components, D ₁ and D _2, for performing a multi-level signal transmission in the one-bit mode. If an 8-level ASK signal is used, as in 68 ₃ , it can be transmitted in a one-bit mode D _1, D ₂ and D ₃ . As it is in 68 is shown, D _{1 is} eight signal points 721a . 721b . 722a . 722b . 723a . 723b . 724a . 724b where each pair represents a two-bit pattern, D ₂ becomes four small signal point groups 721 . 722 . 723 . 724 each two groups represent a two-pattern, and D ₃ becomes two large signal point groups 725 and 726 associated with representing a two-bit pattern. In particular, this is equivalent to a form in which each of the four signal points 721 . 722 . 723 . 724 , in the 57 is divided into two components, so that data with three different levels are generated.

The three-level signal transmission is identical to that described in the third embodiment and will not be explained further in detail.

In particular, the arrangement of the video encoder 401 of the third embodiment, which is in 30 is shown replaced by an amendment whose block diagram 69 is. the operation of the modified arrangement is similar and will not be described in detail. Two video signal divider circuits 404 and 404a which may be sub-band filters are provided and form a divider unit 794 , The divider unit 794 may also be simpler, as shown in the block diagram of FIG 70 is shown in which a signal passes through a single divider circuit twice in a time division mode. More specifically, a video signal of, for example, high-definition television or super-high definition television is input from the input unit 402 with respect to the time base by a timebase compressor 795 compressed and the divider circuit 404 where it is divided into four components H _H V _H -H, H _H V _L -H and H _L V _H -H in a first cycle. There are four switches at this time 765 . 765a . 765 . 765c switched to position 1, so that H _H V _H -H, H _H V _L -H and H _L V _H -H to a compression circuit 405 be transmitted. Meanwhile, H _L V _L -H goes through terminal 1 of the switch 765c to the timebase compressor 795 recycled. In a second cycle, the four switches 765 . 765a . 765b . 767c switched to position 2, and all four components of the divider circuit 404 become simultaneously to the compression circuit 405 transfer. Accordingly, the divider unit 794 of the 70 , which is designed for time division processing of an input signal, can be constructed in a simpler divider circuit form.

On the receiver side, such a video decoder as described in the third embodiment and in 30 shown is needed for the three-level transmission of a video signal. In particular, a third video decoder 423 provided, the two mixers 556 and 556a different processing capability, as shown in the block diagram of 71 is shown.

Also, the third video decoder 423 be modified by the same effect with a single mixer 556 is executed as it is in 72 is shown. For the first time there are five switches 765 . 765a . 765b . 765c . 765d switched to position 1. Therefore, H _L V _L , H _L V _H , H _L V _H and H _H V _H from a first 522 , a second one 522a , a third 522b and a fourth expander 522c through their corresponding switch the mixer 556 where they are mixed into a single video signal. The video signal representing H _L V _L -H of an input high resolution video signal is then passed back through terminal 1 of the switch 765d to port 2 of the switch 765c guided. At the second time, the four switches 765 . 765a . 765b 765c switched to position 2. Thus, H _H V _H -H, H _H V _L -H, H _L V _H -H and H _L V _L -H become the mixer 556 where they are mixed into a single video signal, which then passes through port 2 of the switch 765d to the output unit 554 is sent for further subcontracting.

In this way of time division processing of a three-level signal, two mixers can be replaced by a mixer.

Specifically, four components H _L V _L , H _L V _H , H _H V _L , H _H V _{H are} supplied to generate H _L V _L -H at the first time. Then, H _L V _H -H, H _H V _L -H and H _H V _H -H are supplied at the second time, delayed from the first time, and mixed with H _L V _L -L to a target video signal. It is thus essential to carry out the two effects in a time interval.

If the four components are overlapped or fed in a variable sequence, they must be adjusted for a given sequence in terms of the time base using memories that have their respective switches 765 . 765a . 765b . 765c accompany. In the above manner, a signal is sent from the transmitter to two different synchronizing periods, as shown in FIG 73 is shown, so that no time base control circuit is needed in the receiver, which is thus made more compact.

As it is in 73 D _{1 is} the first data stream of a transmitter signal and H _L V _L , H _L V _H , H _H V _L and H _H V _H are transmitted on the D ₁ channel at the period of the first timing. Then at the period of the second timing H _L V _H -H, H _H V _L -H and H _H V _H -H are transmitted on the D ₂ channel. When the signal is transmitted with a time division sequence, the encoder in the receiver can be made simpler.

The technique of reducing the number of expanders in the decoder will now be explained. 74 Figure-b shows a timebase map of four data components 810 . 810a . 810b . 810c a signal. If other four data components 811 . 811a . 811b . 811c between the four data compilers 811 . 811a . 811b . 811c each introduced, the latter can be transmitted in time intervals. In use, the second video decoder receives 422 who in 74 -A, the four components of the first data stream D ₁ at a first input 521 and transfer them successively through a switch 812 to an expander 503 , In particular, the component supplied first becomes 810 during the feeding of the component 811 expanded and after completion of the component processing 812 becomes the subsequent component 810a fed. Therefore, the expander 503 process a series of components at time intervals by the same time division manner as that of the mixer so as to replace the simultaneous action of a number of expanders.

75 Fig. 10 is a time base map of data components of a high-resolution television signal in which H _L V _L (1) is an NTSC component of the first channel signal for a television program to a data area 821 of the D ₁ signal is allocated. Also, H _L V _H , H _H V _L and H _H V _H carry the additional high-definition television components of the first channel signal, three areas respectively 821a . 821b . 821c assigned to the D ₂ signal. There are more data components 822 . 822a . 822b . 822c between the data components of the signal of the first channel, which can thus be expanded with an expander circuit during the transmission of the other data. Therefore, all the data components of a channel's signal are processed by a single expander that can operate at a higher speed.

Similar effects are achieved by mapping the data components to other areas 821 . 821a . 821b . 821c ensured, as it is in 76 is shown. This becomes more efficient in transmitting and receiving a common QPSK or ASK signal that does not have different digital levels.

77 shows a time base assignment of data components during two-level physical transmission of data at three different signal levels: eg NTSC, HDTV and Super HDTV or NTSC with low resolution, NTSC with HD and HDTV. For example, to transmit three data components of low resolution NTSC, standard NTSC and high definition television, the low resolution NTSC or H _L V _L becomes the data area 821 assigned to the D ₁ signal. Also, H _L V _H , H _H V _L and H _H V _{H of} the NTSC standard component each become three areas 821a . 821b . 821c allocated. H _L V _H -H, H _H V _L -H and H _H V _H -H of the high-definition television component, respectively 823 823a and 823b allocated.

The above assignment is associated with such a logic level arrangement based on a discrimination in the error correction capability as described in the second embodiment. In particular, H _L V _{L is carried} on the D _1-1 channel of the D ₁ signal. The D _1-1 channel has a larger error correction capability than the D _1-2 channel as described in the second embodiment. The D _1-1 channel has greater redundancy but a lower error rate than the D _1-2 channel, and the data 821 can at a lower S / N rate than the other data 821a . 821b . 821c be reproduced. In particular, a low resolution NTSC component is reproduced at a remote location from the special antenna or in a signal attenuating or shadowing area, eg in the interior of a vehicle. With regard to the error rate, the Date 821 of the D _1-1 channel less through the Signal disturbance than the other data 821a . 821b . 821c of the D _1-2 channel while being specifically discriminated and staying at a different logical level as described in the second embodiment. While D ₁ and D _{2 are divided} into two different physical levels, the levels determined by differentiating the distance between error correction codes are arranged differently in the logic level.

The demodulation of D ₂ data requires a higher S / N rate than that for D ₁ data. In operation, a low resolution H _L V _L or NTSC signal may be reproduced at least in a remote or poor S / N coverage area. H _L V _H , H _H V _L and H _H V _H can also be reproduced in a lower S / N range. Then, in a high S / NH _{L range,} V _H -H, H _H V _L -H, and H _H V _H -H components may also be reproduced to produce a high-definition television signal. Accordingly, television signals having three different levels can be reproduced. This method enables the signal reception area included in 53 is shown enlarged from a double area to a triple area, as in 90 is shown, so that a greater possibility is ensured to enjoy television programs.

78 FIG. 12 is a block diagram of the third video decoder configured for the timebase mapping of data stored in 77 are shown, and similar to that in 72 shown with the exception that the third input 551 for the D ₃ signal is omitted and the in 74 -A training is added.

In operation, the D ₁ and D ₂ signals are transmitted through the input units 521 . 530 one switch each 812 fed at the first time. Since their components, which include H _L V _L , are time shared, they are sequenced by the switch 812 to an expander 503 transfer. This sequence will now be described with reference to the timebase assignment of 77 explained. A compressed form of H _L V _{L of} the first channel first becomes the expander 503 fed, where it is expanded. Then H _L V _H , H _H V _L and H _H V _{H are} expanded. All four components are expanded by a switch 812a to a mixer 556 sent where they are mixed to produce H _L V _L -H. H _L V _L -H is then from the port 1 a switch 765a through the entrance 2 a switch 765 to the H _L V _L input of the mixer 556 recycled.

At the second time point H _L V _H -H, H _H V _L -H and H _H V _{H of} the D ₂ signal, which in 77 shown is the expander 503 fed to where they are to be expanded before going through the switch 821a to the mixer 556 be transmitted. They are going through the mixer 556 mixed into a high definition television signal passing through port 2 of the switch 765a the output unit 521 for further distribution. The timebase mapping of data components transmission, which in 77 is shown contributes to the simplest configuration of the expander and the mixer. Although 77 2, D ₁ and D ₂ shows signal level, four-level transmission of a television signal is feasible using the addition of a D ₃ signal and super-resolution television signal of super-resolution.

79 Fig. 10 illustrates a time base map of data components of a three-level physical television signal D _1, D _2, D ₃ in which data components of the same channel are arranged so as not to overlap each other with time. 80 is a block diagram of a modified video decoder 423 similar to the 78 in which a third entrance 521 is added. The timebase mapping of the data components that are in 79 also contributes to the simple construction of the decoder.

The operation of the modified decoder 423 is almost identical to the one in 78 and is associated with the timebase assignment that is in 77 is shown, and is no longer explained. It is also possible to multiplex data components on the D ₁ signal as shown in FIG 81 is shown. However, the two dates become 821 and 822 greater error correction capability than the other data components 821a . 812b . 812c increased so that they remain at a higher signal level. In particular, the data allocation is made for transmission at a physical level, but a relationship of two logical levels. Also, each data component of the second channel is inserted between two adjacent data components of the first channel, so that serial processing can be performed on the receiver side, and the same effects as those of the timebase assignment shown in FIG 79 is shown are thus obtained.

The timebase mapping of data components that are in 81 is based on the logic level mode and can also be executed in the physical level mode when the bit transmission rate of the two data components 821 and 822 is lowered to 1/2 or 1/3, thereby reducing the error rate. The physical level arrangement consists of three different levels.

82 is a block diagram of another modified video decoder 423 for decoding the D ₁ signal, arranged on a time base basis is how it is in 81 what is a simpler design than the one shown in 80 shown is. Its mode of operation is identical to that of the decoder, which in 80 is shown, and is no longer explained.

It will be appreciated that the timebase mapping of data components stored in 81 also contributes to the simple design of the expander and mixer. Also, four data components of the D ₁ signal at respective time slices become a mixer 556 fed. Therefore, the circuit design of the mixer 556 or a plurality of circuit blocks as used in the video mixer 548 of the 32 is arranged to change the connection therebetween corresponding to each data component, so that they become compatible in the time division action, and thus the circuit construction is minimized.

Accordingly, the receiver be minimized in the overall construction.

It understands that the fifth Aüsführungsform not limited to the ASK modulation, and the other procedures, including PSK and QAM modulation as in the first, second and third embodiment have been described, can be used with equal success.

Also, the FSK modulation is in each of the embodiments in question. For example, the signal points of a multi-level FSK signal consisting of four frequency components f1, f2, f3, f4 are divided into groups as shown in FIG 58 is shown, and when the distance between any two groups is spaced apart from each other for easy discrimination, the multi-level transmission of the FSK signal can be performed as shown in FIG 83 is shown.

In particular, it is assumed that the frequency group 841 with f1 and f2 D ₁ = 0 is assigned and the group 842 with f3 and f4 D ₁ = 1 is assigned. When f1 and f3 represent 0 at D ₂ and f2 and f4 represent 1 at D ₂ , a two-bit data transfer, one bit at D ₁ or D _2, becomes possible as shown in FIG 83 is shown. If the S / N rate is high, a combination of D ₁ = 0 and D ₂ = 1 is reconstructed at t = t3 and a combination of D ₁ = 1 and D ₂ = 0 at t = t 4. When the S / N rate is low, only D ₁ = 0 is reproduced at t = t3 and D ₁ = 1 at t = t4. In this way, the FSK signal can be transmitted in the multi-level arrangement. This multi-state FSK signal transmission is applicable to the respective third, fourth and fifth embodiments.

The fifth embodiment can also be embodied in the form of a magnetic recording / reproducing apparatus, of which a block diagram in FIG 84 is shown because the ASK mode operation is suitable for a magnetic recording and reproducing operation.

Embodiment 6

A sixth embodiment The present invention is directed to a magnetic recording and reproducing apparatus applicable. Although the above described fifth Embodiment the The present invention relates to a multi-level recording ASK data transmission system It is equally feasible to use this invention in a magnetic recording and reproducing apparatus of a Multi-level ASK recording system to take over. A multi-level magnetic recording can be achieved by incorporating the C-CDM system of the present invention realized in PSK, FSK, QAM and ASK become.

First of all, the method of realizing multi-level recording in a 16QAM or 32QAM magnetic recording reproducing apparatus will be explained with reference to the C-CDM system of the present invention. 84 Fig. 12 is a circuit block diagram showing a QAM system including a C-CDM modulator. Hereinafter, a QAM system which is multiplexed by the C-CDM modulator will be referred to as SRQAM.

As it is in 84 1, an input video signal, eg, an HDTV signal, becomes a magnetic recording / reproducing apparatus 851 divided and by a video encoder 401 in a low frequency band signal by a first video encoder 401 (a) or a high frequency band signal by a second video encoder 401 (b) compressed. Then, a low frequency band component, eg, H _L V _L , of the video signal of a first data stream input 743 an input unit 742 and a high frequency band component including H _H V _H is applied to a second data stream input 744 supplied from it. The two components also become a modulator 749 a modulator / demodulator unit 852 transfer.

The first data stream input 743 adds an error correction code in an ECC to the signal in the low frequency band 743a added. On the other hand, the second data stream is the second data stream input 744 2 bits in the case of 16 SRQAM, 3 bits in the case of 36 SRQAM and 4 bits in the case of 64 SRQAM. Having an error correction code in an ECC 744a This signal is sent to a trellis encoder 744b in which a trellis coded signal is generated which has a ratio 1/2 in the case of 16 SRQAM, 2/3 in the case of 32 SRQAM and 3/4 in the case of 64 SRQAM. One 64 For example, SRQAM signal has an ers 2-bit data stream and a 4-bit second data stream. A trellis encoder from 128 allows this 64 SRQAM signal to perform 3/4 ratio trellis encoding, converting 3-bit data into 4-bit data. This increases the redundancy and the data rate decreases as the error correction capability increases. This results in a reduction of the error rate at the same data rate. Accordingly, the amount of transferable information of the recording / reproducing system or the transmission system will increase significantly.

It is possible, however, the first data stream input 743 to exclude a trellis encoder, as in 84 of this sixth embodiment, since the first data stream inherently has a low error rate. This will be advantageous in view of simplifying the circuit configuration. However, the second data stream has a narrow inter-code distance compared to the first data stream, and therefore has a worse error rate. The trellis encoding of the second data stream improves such a worse data rate. There is no doubt that an overall circuit configuration becomes simpler if the trellis encoding of the first data stream is eliminated. An operation for modulation is almost identical to that of the transmitter of the fifth embodiment disclosed in FIG 64 is shown, and will not be explained further. A modulated signal of the modulator 749 becomes a record / replay circuit 853 fed in by a grid bias generator 856 AC-biased and through an amplifier 857a is reinforced. Thereafter, the signal becomes a magnetic head 854 for recording on a magnetic tape 855 fed.

A format of the recording signal is in a recording signal frequency assignment of 113 shown. A main signal 859 , eg SRQAM, with a carrier of frequency fc records information, and at the same time also a pilot signal f _p 859a with a frequency 2k recorded. Distortions in the recording operation are reduced because of a bias signal 859b adds an AC bias to the magnetic recording at a frequency f _{B IAS} . Two of the three-level signals in 113 are recorded in multiple states. To reproduce these recorded signals, two thresholds Th-1-2, Th-2 are given. A signal 858 will reproduce both of the two levels while receiving a signal 859c only reproduce D ₁ data, depending on the S / N level of the recording / playback.

A main signal of 16 SRQAM will have a signal point assignment as shown in lane 10 is shown. Furthermore, a main signal of 36 SRQAM will have a signal point assignment as shown in FIG 100 is shown. When reproducing this signal will be the main signal 859 and the pilot signal 859a through the magnetic head 854 reproduced and through an amplifier 857b strengthened. An output signal of the amplifier 857b becomes a carrier reproduction circuit 858 fed, in which a filter 858h the frequency of the pilot signal f _p , which has a frequency 2f02, disconnects, and a ½ frequency divider 858b reproduces a carrier frequency f0 to a demodulator 760 transferred to. This reproduced carrier is used to produce the main signal in the demodulator 760 to demodulate. Provided that a magnetic recording tape 855 For example, an HDTV tape has a high S / N rate, 16 signal points are distinguishable, and so both D ₁ and D _{2 become} in the demodulator 760 demodulated. Subsequently, a video decoder reproduces 402 all these signals. An HDTV VCR can reproduce a high bit rate television signal, such as a 15Mbps HDTV signal. The lower the S / N rate, the lower the cost of a videotape. So far, a VHS in the market is more than 10dB lower in S / N rate than a full-scale transmission band. If a videotape 855 has a low S / N rate, it will not be able to distinguish all the 16 or 32 valued signal points. Therefore, the first data stream D _{1 can be} reproduced while a 2-bit, 3-bit or 4-bit data stream of the second data stream D ₂ can not be reproduced. Only a 2-bit data stream of the first data stream is reproduced. When a bilevel HDTV video signal is recorded and reproduced, a low S / N band having insufficient ability to reproduce a high frequency band video signal may output only a low frequency band low frequency band video signal, specifically, for example a 7Mbps wide NTSC television signal.

As in a block diagram of 114 can be shown, the second data stream output 759 , the second data stream input 744 and the second video decoder 402a be excluded to provide customers with an aspect of lower grade products. In this case, a recording / reproducing apparatus becomes 851 , which is dedicated to a low bit rate, includes a modulator, such as a modified QPSK, which modulates and demodulates only the first data stream. This device only allows recording and reproduction of the first data stream. Specifically, a video signal of wide NTSC grade can be recorded and reproduced.

Above described videotape 855 high S / N rate capable of recording a high bit rate signal, eg an HDTV signal, is the use in such a magnetic recording / reproducing apparatus dedicated to a bit rate; but will only reproduce the first data stream D ₁ . That is, the wide NTSC signal is output while the second data stream is not reproduced. In other words, a recording / reproducing apparatus having a complicated configuration can reproduce an HDTV signal, and the other recording / reproducing apparatus having a simple configuration can reproduce a wide NTSC signal when a given video tape 855 includes the same multi-level HDTV signal. Accordingly, in the case of two-level multiple states, four combinations having perfect compatibility between two bands, the different S / N rates and two recording / reproducing apparatuses having different recording / reproducing data rates are realized. This will bring a remarkable effect. In this case, a device dedicated to NTSC will be simple in construction as compared with a device dedicated to HDTV. In detail, a switching scale of the EDTV decoder will be 1/6 of the switching scale of an HDTV decoder. Therefore, a low-function device can be realized at a rather low cost. The realization of two types of recording / reproducing apparatuses, HDTV and EDTV, with different image quality reproducibility / reproducibility will provide products of various types which are in a wide price range. Users can freely select a band among a plurality of bands, from an expensive high S / N rate band to a lower S / N rate cheaper band, as occasion demands, to a required picture quality to fulfill. Not only does it maintain perfect compatibility, but it also achieves scalable capability and ensures further compatibility with a future system. Consequently, it will be possible to establish long-lasting standards for recording / reproducing apparatus. Other recording methods will be used in the same way. For example, multi-level recording will be realized by using a phase modulation as explained in the first and third embodiments. A recording using ASK as explained in the fifth embodiment will also be possible. A multiple state will be realized by converting the current two-level to four-level recording and dividing it into two groups, such as the 59 (c) and 59 (d) is shown.

A circuit block diagram for ASK is identical to that in FIG 84 disclosed. Besides embodiments already described, multi-level recording will also be realized by using multiple tracks on a magnetic tape. Further, theoretical multi-level recording becomes feasible by discriminating the error correction ability so as to discriminate corresponding data.

Compatibility with future ones Standards will be described below. Setting standards for recording / playback devices How a VCR is usually considered in practice available Bandes with the highest S / N rate performed. The recording characteristics of tapes are progressing rapidly. For example, the S / N rate is more than 10dB compared to The band used 10 years ago has been improved. If accepted will that new standards after 10 to 20 years due to progress The band feature will become a conventional one Procedures have difficulty getting compatibility with older standards. Indeed are new and old standards for usually unidirectionally compatible or not compatible with each other. In contrast, according to the present Invention the standards first for recording and / or reproducing the first data stream and / or of the second data stream on current bands. After that, if the S / N rate in the future to a great extent is improved, a higher level data stream, e.g. a third Data stream, without any difficulty being added, as long as the present invention is incorporated in the system. For example, a super HDTV VCR that is capable of one Three-level 64 SRQAM signal to record or reproduce, at Maintaining perfect compatibility with the traditional ones Standards are realized. A magnetic tape, the first third streams according to new standards records, of course, becomes also be able to in the older Biplane Magnetic Reproduction / Recording Device used for Be the first to record / reproduce only streams be able to. In this case, first and second data streams can be perfect are reproduced, although the third stream is not reproduced is left. Therefore, an HDTV signal can be reproduced. For these reasons is due to the expansion of the scope of record data while maintaining the compatibility between new and old Standards expected.

Returning to the explanation, the playback operation of 84 reproduce the magnetic head 854 and the magnetic reproduction circuit 853 a reproduction signal from the magnetic tape 855 and carry it to the modulation / demodulation circuit 852 to. The demodulation operation is approximately identical to the first, third and fourth th embodiment and will not be explained further. The demodulator 760 reproduces the first and second data streams D ₁ and D ₂ . The second data stream D ₂ is error corrected with high code gain in a trellis decoder 759b such as a vitamin encoder, to have a low error rate. The video decoder 402 D ₁ and D ₂ demodulate signals to output an HDTV video signal.

131 Fig. 10 is a block diagram showing a three-level magnetic recording / reproducing apparatus according to the present invention having a theoretical level in addition to two physical levels. This system is essentially the same as that of 84 , The difference is that the first data stream is further divided into two auxiliary channels by using a TDM to realize a three-level construction.

As in 131 is shown, an HDTV signal is first in two video signals in the middle and low frequency band D _1-1 and D _1-2 by a 1-1 video encoder 401c and a 1-2 video encoder 401d is divided and then a first data stream input 743 the first entrance section 742 fed. The data stream D _1-1 having picture quality at MPEG rate is error correction coded with high code gain in an ECC coder 743a while the data stream D _1-2 error correction encodes with normal code gain in an ECC encoder 743b is. D _1-1 and D _1-2 are time-multiplexed together in a TDM 743c to give a data stream D ₁ . D ₁ and D ₂ are in two level signals in a C-CDM 749 modulated and then on the magnetic tape 855 by means of the magnetic head 854 recorded.

In the reproduction operation, a recording signal generated by the magnetic head 854 is reproduced in D ₁ and D ₂ by a C-CDM demodulator 760 in the same way as in the explanation of 84 demodulated. The first data stream D ₁ is divided into two subchannels D _1-1 and D _1-2 by means of the TDM 758C which is in the first data stream output 758 is provided, demodulated. The D _1-1 data is stored in an ECC decoder 758a that has a high code gain, error-corrected. Therefore, the D _1-1 data can be demodulated at a lower S / N rate compared to the D _1-2 data. A 1-1 video decoder 402a decodes the D _1-1 data and outputs an LDTV signal. On the other hand, the D _1-2 data in an ECC decoder 758b which has a normal code gain, error-corrected. Therefore, the D _1-2 data has a high S / N rate threshold compared to the D _1-1 data and therefore will not be demodulated if a signal level is not large. The D _1-2 data will then be in a 1-2 video decoder 402d demodulated and summed with the D _1-1 data to output an EDTV signal of wide NTSC grade.

The second data stream D ₂ is Vitabi demodulated in a trellis decoder 759b and error corrected in an ECC decoder 759a , Therefore, D ₂ data becomes a video signal in the high frequency band by means of a second video decoder 402b and then summed with the D _1-1 and D _1-2 data to output an HDTV signal. In this case, a threshold value of the S / N rate of the D ₂ data is set larger than that of the S / N rate of the D _1-2 data. Accordingly, D _1-1 data, that is, an LDTV signal, becomes a band 855 having a smaller S / N rate can be reproduced. D _1-1 and D _1-2 data, ie an EDTV signal, is from a band 855 having a normal S / N rate to be reproduced. And D _1-1 D _1-2 and D ₂ data, ie, an HDTV signal, will be reproduced from a tape having a high S / N rate.

Three-level magnetic recording / playback devices can be realized in this way. As in the above description has been described, the band 855 has a correlation between S / N rate and costs. The present invention allows users to according to one Content of a TV program you want to record, one To select the degree of a band because video signals that have image qualities of three degrees, in accordance recorded and / or reproduced at the cost of the tape.

Next, an effect of multi-level recording on fast feed reproduction will be described. As in a recording track diagram of 132 is a recording track 855a having an azimuth angle A and a recording track 855b having an opposite azimuth angle B alternately on the magnetic tape 855 bayed. The recording track 855a has a recording area 855c at its central portion and the rest as D _1-2 recording areas 855D as indicated in the drawing. This unique recording pattern is provided on at least one of the multiple recording tracks. The recording area 855c records a frame of the LDTV signal. A signal D ₂ in the high frequency band is on a D ₂ recording area 855e the entire recording area of the recording track 855a corresponds, recorded. This recording format brings no new effect against a normal speed recording / reproducing operation.

Fast reverse reproduction in the reverse direction does not allow magnetic head progression 855f with an azimuth angle A, coincide with the magnetic track, as shown in the drawing is. Since the present invention, the D _1-1 recording area 855c at a central narrow portion of the magnetic tape provides, as in 132 is shown, only this area is surely reproduced although it appears with a predetermined probability. The D _1-1 signal reproduced in this way can demodulate a complete picture plane of the same time although its picture quality is an LDTV of the MPEG1 level. In this way, several to several tens of LDTV signals with perfect images can be reproduced during the fast feed reproduction operation, thereby enabling users to securely confirm images during the fast feed operation.

A head course 855g corresponds to a head history in the reverse playback operation, whereby it will be understood that only a portion of the magnetic track is tracked in the reverse playback operation. This in 432 However, the recording / reproducing format shown allows to reproduce the D _1-1 recording area even in such a reverse reproducing operation, and therefore an LDTV-degree animation is output at intervals.

Accordingly, it allows the present invention, an image representation of the LDTV grade within of a narrow area on the recording track, what in a reproduction at intervals almost perfect still images with LDTV grade image quality while normal and reverse fast feed playback operation results. Thereby can Users easily displayed images even in high-speed search to confirm.

Next, another method to address a high-speed fast-feed playback operation will be described. A D _1-1 , recording area 855c is as below right from 132 is shown, so that a frame of an LDTV signal is recorded therein. Furthermore, a narrow D _1-1 D2 recording area 855H in a part of the D _1-1 recording area 855c intended. A sub channel D _1-1 in this area records part of the information relating to the one frame of the LDTV signal. The rest of the LDTV information becomes in the D ₂ recording area 855j of the D _1-1 . D ₂ recording area 855H recorded in a duplicate way. The auxiliary channel D ₂ has a data recording capacity three to five times as large as that of the auxiliary channel D _1-1 . Therefore, the auxiliary channels D _1-1 and D _{2 can} record frame information of the LDTV signal on a smaller (1/3/1/5) area of the recording tape. Because the head course in even narrower areas 855H . 855j can be recorded, time and range are reduced by 1 / 3-1 / 5 compared to a head trace time T _S1 . Even if the course of the head is further inclined by increasing the fast feed speed amount, the likelihood of tracking this area will be increased. Accordingly, perfect LDTV image representations are reproduced at intervals even if the fast feed speed is increased up to 3 to 5 times as much as in the case of only the subchannel D _1-1 .

In the case of a bi-level VCR, this process is in the reproduction of the D ₂ recording area 855j useless, and therefore this area is not reproduced in a high speed fast feed reproducing operation. On the other hand, a high-performance three-level VCR will allow users to confirm an image representation even when a fast-forward playback operation is performed at a higher speed three to five times that of the two-level VCR. In other words, not only excellent image quality is obtained in accordance with cost, but a maximum fast-feed speed that enables the reproduction of image images can be increased in accordance with the cost.

Even though this embodiment does not need to be said to use a multilevel modulation system be that a normal, e.g. 16 QAM, modulation system, taken can be to the Schnellvorschubwiedergabeoperation according to the present To realize invention, insofar as a coding of image representations is of multiple type.

A recording method of a conventional non-multiple digital VCR in which picture representations are highly compressed distributes video data uniformly. Therefore, it was not possible to reproduce all the image representations of an image plane of the same time in a fast feed reproducing operation. The reproduced image was that which consisted of a plurality of image rendering blocks that had non-coincident time bases. However, the present invention provides a multi-level HDTV VCR which can reproduce image display blocks having coincident time bases on an entire image plane during a fast feed reproducing operation, though its picture quality is of the LDTV degree. The three-level recording according to the present invention will enable the reproduction of a high-definition television signal such as an HDTV signal when the recording / reproducing system has an S / N rate. Meanwhile, an EDTV-grade television signal such as a wide NTSC signal or an LDTV-grade television signal such as a low-resolution NTSC signal is reproduced when the recording / reproducing system has a low S / N rate or is of a lesser function. As described in the foregoing description, the magnetic recording / reproducing apparatus according to the present invention can reproduce image representations consisting of the same content even when the S / N rate is low or an error rate is high, although the resolution or image quality is relatively low ,

Embodiment 7

A seventh embodiment of the present invention will be described for carrying out four-level video signal transmission. A combination of the four-level signal transmission and the four-level video data construction generates a four-level signal coverage area as shown in FIG 91 is shown. The four-level supply area consists of a first from the inside 890a , a second one 890b , a third 890c and a fourth signal receiving area 890d , The method for developing such a four-level transmission range will be explained in more detail.

The four-level arrangement can be performed by using four physical, different levels, which are determined by modulation, or four logic levels, the defined by data discrimination in the error correction capability are. The former gives a big difference to the S / N Rate between two adjacent levels and the S / N rate needs to be increased to distinguish all four levels from each other. The latter is underlying the effect of demodulation, and a difference in the S / N rate between adjacent levels should stay at a minimum. Therefore, the four-level arrangement is best constructed by a combination of two physical levels and two logical levels Levels is used. The subdivision of a video signal into four Signal level is explained.

93 is a block diagram of a divider circuit 3 that is a video divider circuit 895 and four compressors 405a . 405b . 405c . 405d includes. the video splitter circuit 895 contains three divider circuits 404a . 404b . 404c which is identical to the divider circuit 404 of the first video encoder 401 are trained in 30 is shown and will not be explained. An input video signal is divided into four components by the divider circuit, H _L V _L for low resolution data, H _H V _H for high resolution data and H _L V _H and H _H V _L for medium resolution data. The resolution of H _L V _L is half that of the original input signal.

The input video signal is first through the divider circuit 404a divided into two, one high and one low frequency band component, each of which is divided into a horizontal and a vertical portion. The intermediate parts between the high and the low frequency ranges is a dividing point according to the embodiment. Therefore, if the input video signal is a high definition television signal having a vertical resolution of 1000 lines, H _L V _L has a vertical resolution of 500 lines and a horizontal resolution of half the value.

Each of the two data, horizontal and vertical, of the low frequency component H _L V _L is passed through the divider circuit 404c divided into two frequency band section. Therefore has a H _L V _L section output 250 Lines of vertical resolution and 1/4 of the original, horizontal resolution. This output of the divider circuit 404c , which is referred to as an LL signal, is then passed through the compressor 405a compressed to a D _1-1 signal. The other three higher frequency sections of H _L V _L are through a mixer 772c mixed to a LH signal, then through the compressor 405b is compressed to a D _1-2 signal. The compressor 405b can be replaced by three compressors between the divider circuit 404c and the mixer 772c are provided.

H _L V _H , H _H V _L and H _H V _H from the divider circuit 404a be through a mixer 772a mixed to a H _H V _H -H signal. When the input signal is as high as 1000 lines in horizontal and vertical resolution, H _H V _H -H has 500 to 1000 lines of horizontal and vertical resolution. H _H V _H -H becomes the divider circuit 404b where it is again divided into four components.

Similarly, H _{L has} V _L of the divider circuit 404b 500 to 750 lines of horizontal and vertical resolution, and is used as an HL signal to the compressor 405c about asking.

The other three components H _L V _H , H _H V _L and H _H V _H from the divider circuit 404b have 750 to 1000 lines of horizontal and vertical resolution and are controlled by a mixer 772b mixed to a HH signal, then through the compressor 405d is controlled and delivered as D _2-2 signal. After compression, the HL signal is provided as a D _2-1 signal. As a result, LL or D _1-1 carries a frequency data of 0 to 250 lines, LH or D _1-2 carries a frequency data of more than 250 lines up to 500 lines, HL or D _2-1 carries a frequency data of more than 500 lines up to 750 lines and HH or D _2-2 carries a frequency data of more than 750 lines to 1000 lines, so that the divider circuit 3 can produce a four-level signal. Accordingly, when the divider circuit 3 the transmitter 1 , in the 87 is shown by the divider circuit of 93 is replaced, the transfer of a Four-level signal executed.

The combination of multi-level data and multi-level transmission enables a video signal to be gradually deteriorated in image quality in proportion to the S / N rate during transmission, thereby contributing to the enlargement of the television service area. At the receiver side, the operation of demodulation and recovery is identical to that of the second receiver of the second embodiment disclosed in US Pat 88 is shown and no longer explained. In particular, the mixer 37 modified for video signal transmission instead of data communication and will now be explained in more detail.

As has been described in the second embodiment, after being demodulated and error-corrected, a received signal is sent to the mixer as a group of four components D _1-1, D _1-2, D _2-1, D _2-2 37 of the second receiver 33 of the 88 fed.

94 is a block diagram of a modified mixer 33 in which D _1-1, D _1-2, D _2-1, D _2-2 through their respective expander 523a . 523b . 523c . 523d are each expanded to an LL, an LH, an HL and an HH signal, which are equivalent to those associated with 93 have been described. When the bandwidth of the input signal 1 LL has a bandwidth of 1/4, LL + LH has a bandwidth of 1/2, LL + LH + HL has a bandwidth of 3/4 and LL + LH + HL + HH has a bandwidth of 1. The LH Signal is then passed through a divider circuit 531a divided and by a video mixer 548a mixed with the LL signal. An output of the video mixer 548a becomes a H _L V _L connection of a video mixer 548c transfer. The video mixer 531a is identical to that of the second decoder 527 of the 32 and is no longer explained. Also, the HH signal is by a divider circuit 531b divided and a video mixer 548b fed. At the video mixer 548b is mixed to a H _H V _H -H signal, the HH signal with the HL signal which is then divided by a divider circuit 531c shared and to the video mixer 548c is sent. At the video mixer 548c H _H V _H -H is combined with the sum signal of LH and LL to form a video output. The video output of the mixer 33 then becomes the output unit 36 of the second receiver transmitted in 88 shown where it is converted into a television signal for delivery. If the original signal has 1050 lines of vertical resolution or is a high resolution television signal with a resolution of about 1000 lines, its four different signal level components can be received in their respective signal receiving areas, as shown in FIG 91 is shown.

The image quality of the four different components will be described in more detail. The presentation of the 92 is a combination of 86 and 91 again. As is apparent, as the S / N rate increases, the overall signal level or the size of the data from 862D on 862a increased in increments of four signal levels D _1-1, D _1-2, D _2-1, D _2-2 .

Also, as it is in 95 4, the four different level components LL, LH, HL and HH are accumulated in proportion to the S / N rate. More specifically, the quality of a reproduced image is increased as the distance from a transmitter antenna becomes small. If L = Ld, the LL component is rendered. When L = Lc, the LL + LH signal is reproduced. When L = Lb, the LL + LH + HL signal is reproduced. When L = La, the LL + LH + HL + HH signal is reproduced. As a result, if the bandwidth of the original signal 1 , the picture quality is enhanced at 1/4 steps of the bandwidth of 1/4 to 1 depending on the receiving area. If the original signal is a high definition television with 1000 lines of vertical resolution, the reproduced television signal has 250, 500, 750 and 1000 lines of resolution in its respective receiving areas. The image quality is thus changed in steps depending on the level of a signal. 96 Figure 12 shows the signal propagation of a conventional digital high definition television signal transmission system where no signal reproduction is possible when the S / N rate is less than Vo. Also, the signal reception is hardly guaranteed in the signal interference areas, the shadow areas and other signal attenuating areas indicated by the symbol x of the coverage area. 97 shows the signal propagation of a high definition television signal transmission system of the present invention. As shown, the image quality has a full 1000 line quality at the distance La where S / N = a, a 750 line quality at the distance Lb where S / N = b, a 500 line quality at the distance Lc where S / N = c, and a 250 line quality at the distance Ld, where S / N = d. Within the distance La there are some unfavorable areas where the CN rate drops sharply and no high resolution television quality image is reproduced. It is understood, however, that a signal of lesser picture quality may be received and reproduced according to the multi-level signal transmission system of the present invention. For example, the image quality is a 750 line quality at point 8 in a building shadow area, a 250 line quality at point Din a moving train, a 750 line quality at point F in a ghosting area, a 250 line quality at point G in a moving car and a 250-line quality at the point L in the noise area of a neighboring signal. Like it has been stated above, the signal transmission system of the present invention enables a television signal to be successfully received with a quality in the range where the conventional system is poorly qualified, so that its service area is increased. 98 shows an example of the simultaneous transmission of four different television programs, in which three quality programs C, B, A are transmitted on their respective channels D _1-2, D _2-1, D _2-2 , while a diagram D is identical to that a local, analog television station is spread on the D _1-1 channel. Accordingly, while the routine D is kept available with a concurrently broadcast service, the other three programs may also be broadcast in the air to offer a multiple program broadcast service.

Embodiment 8

following becomes an eighth embodiment of the present invention with reference to the drawings explained. The eighth embodiment uses a multi-level signal transmission system the present invention for transmission / Receive in a wireless phone system.

115 is a block diagram showing a transceiver of a portable telephone in which a Telefonkonversationston that via a microphone 762 is entered in a compressor 405 in multi-level data D ₁ , D ₂ and D _{3 is} compressed and coded as described above. These D ₁ , D ₂ , and D ₃ data are time-divided in a time divider circuit 765 in predetermined time slots and thereafter in a modulator 4 into a multi-level signal, eg SRQAM, as described above. Then send an antenna sharing unit 764 and an antenna 22 a carrier wave carrying a modulated signal, which is received by a base station, which will be described later, and transmitted to other base stations or a central telephone exchanger to communicate with other telephones.

In contrast, the antenna receives 22 Broadcast radio waves from other base stations as communication signals from other phones. A received signal is in a demodulator 45 of the multi-level type, eg SRQAM, in D _1, D ₂ and D ₃ data demodulated. A timing circuit 767 detects timing signals based on demodulated signals. These timing signals become the time divider circuit 765 fed. Demodulated signals D ₁ , D ₂ and D ₃ become an expander 503 fed and spread in a sound signal, which then to a speaker 763 transmitted and converted to sound.

116 shows a block diagram showing an example of an arrangement of base stations in which three base stations 771 . 772 and 773 in the center of corresponding receiving cells 768 . 769 and 770 a hexagon or circle are placed. These base stations 771 . 772 respectively. 773 have a plurality of transceiver units 76a - 76j which are similar to those of 115 to have data communication channels corresponding to the number of these transceiver units. A base station controller 774 is connected to all the base stations and always monitors a communication traffic volume of each base station. Based on the monitoring result, the base station controller performs 774 a comprehensive system control including the allocation of channel frequencies to respective base stations or the control of reception cells of respective base stations.

117 Fig. 13 is a view showing a traffic distribution of the communication volume in a conventional, eg QPSK, system. A diagram d = A shows data 774a and 774b having a frequency utilization efficiency of 2 bits / Hz, and a graph d = B shows data having a frequency utilization efficiency of 2 bits / Hz, and a graph d = B shows data 774c which have a frequency utilization efficiency of 2 bits / Hz. A summation of this data 774a . 774b and 774c yields data 774d that represent a transmission amount of Ach, which consists of receive cells 768 and 770 consist. The frequency utilization efficiency of 2 bits / Hz is evenly distributed. However, the population density in an actual urban area is locally large in several crowded areas 775a . 775b and 775c which include concentrated buildings. dates 774 , which represent a communication traffic volume, show multiple peaks at positions that are exactly those crowded areas 775a . 775b and 775c in contrast to other areas that have a low scope of communication. A capacity of a conventional wireless telephone was set equally to 2-bit / Hz frequency efficiency of the entire region as by the data 774d regardless of an actual traffic volume Tf, which is indicated by the data 774e is shown. It is not effective to give the same frequency efficiency regardless of the actual traffic volume. To compensate for this inefficiency, the conventional systems have allocated many frequencies to the regions having a large traffic volume, have increased the channel number or reduced the receiving cell thereof. However, an increase in the number of channels is limited by the frequency spectrum. Furthermore, conventional multilevel mode transmission systems, eg 16 QAM or 64 QAM, increase the transmission power. A reduction in receive cells will increase the number of base stations which will increase the set-up costs.

It is ideal for improving the overall system efficiency to increase the frequency efficiency of the region having a larger traffic volume and to lower the frequency efficiency of the region having a smaller traffic volume. A multi-level signal transmission system according to the present invention realizes this ideal modification. This is by reference to 118 which illustrates a communication scope and a traffic distribution according to the eighth embodiment of the present invention.

Exactly shows 118 Communication scopes of corresponding receiving cells 770b . 768 . 769 . 770 and 770a taken along a line A-A '. The reception cells 768 and 770 use frequencies of a channel group A, while the receiving cells 770b . 769 and 770a Use frequencies of a channel group B that does not overlap with channel group A. The base station controller 774 , in the 116 is shown increases or decreases the channel number of these channels in accordance with the traffic volume of respective receiving cells. In 118 A diagram d = A represents a distribution of a communication volume of the A channel. A diagram d = B represents a distribution of a communication volume of the B channel. A diagram d = A + B represents a distribution of a communication range of all channels. A diagram Tf represents a communication traffic volume, and a diagram P shows a distribution of buildings and population.

The reception cells 768 . 769 and 770 apply the multi-level signal transmission system, eg SRQAM. Therefore, it is possible to obtain a frequency utilization efficiency of 6 bits / Hz, three times as large as 2 bits / Hz of QPSK, in the vicinity of the base stations, as by data 776a . 776b and 776c is designated. Meanwhile, the frequency utilization efficiency decreases in steps of 6 bits / Hz to 4 bits / Hz, and from 4 bits / Hz to 2 bits / Hz when going into the suburban area. When the transmission power is insufficient, 2-bit / Hz areas become narrower than the reception cells of QPSK, indicated by dotted lines 77a . 77b . 77c , However, an equivalent reception cell is easily obtained by slightly increasing the transmission power of the base stations.

The transmission / reception operation a mobile station that is capable of receiving a 64 SRQAM signal is performed by using a modified QPSK which by setting a shift amount from SRQAM to S = 1 at one remote from the base station by use a 16 SRQAM at a location not so far from the same location and a 64 SRQAM at the closest location. Correspondingly increases the maximum transmission power compared to QPSK not.

Further, transceivers are of the 4 SRQAM type whose circuit configuration is simplified in a block diagram of FIG 121 shown is able to communicate with other phones while maintaining compatibility. This will also be the case in a transmitter / receiver of the SRQAM type, as shown in a block diagram of 122 is shown. As a result, there are provided three telephones of different types having different modulation systems. A small size and light weight are important for portable phones. In this regard, the 4 SRQAM systems, which have a simple circuit configuration, will be suitable for the users who want a small and light telephone, although its frequency usage efficiency is low and therefore the cost of a call can increase. In this way, the system according to the invention may be suitable for a wide variety of uses.

As explained above, the transmission system that has a distribution such as d = A + B of 118 whose capacity is changed locally realized. Therefore, an overall frequency use efficiency is effectively greatly improved when the layout of base stations is determined to be appropriate for the actual traffic volume designated by Tf. The effect of the present invention will be particularly great in a microcell system whose receiving cells are smaller and therefore require a plurality of auxiliary base stations, since a large number of auxiliary base stations can be easily installed in a location having a large traffic volume.

Next, the data assignment of each time slot will be explained with reference to FIG 119 explains 119 (a) a conventional timeslot and 119 (b) show a time slot according to the eighth embodiment. The conventional system performs a downlink transmission, ie, from a base station to a mobile station, as in FIG 119 (a) is shown, in which a synchronization signal S by a time slot 718 (a) and transmit signals to corresponding portable telephones of A, B, C channels through time slots 780 (b) . 780 (c) respectively. 780 (d) be transmitted at a frequency A. On the other hand, an uplink transmission, ie from the mobile station to the base station, is performed such that a synchronization signal and transmission signals of a, b, c channels through time slots 781 (a) . 781 (b) . 781 (c) . 781 (d) be transmitted at a frequency B.

The present invention, which is characterized by a multi-level signal transmission system, eg 64 SRQAM, allows three-level data consisting of D ₁ , D ₂ , D ₃ of 2 bits / Hz, as in 119 (b) is shown to have. Since both of the A ₁ and A ₂ data are transmitted through 16 SRQAM, their time slots have twice the data rate as slots 782 (b) . 782 (c) and 783 (b) . 783 (c) is shown. This means that sound of the same quality can be transmitted in half the time. Accordingly, a time width of corresponding time slots becomes 782 (b) . 782 (c) half the size. In this way, a double transmission capacity in the two-level area 776 who in 118 is shown, ie in the vicinity of the base station, can be achieved.

Time slots lead in the same way 782 (g) . 783 (g) transmitting / receiving E1 data using a 64 SRQAM signal. Since the transmission capacity is three times as large, a time slot for three channels of E ₁ , E ₂ , E ₃ can be used. This would be used for a region even closer to the base station. As a result, a communication capacity up to three times greater in the same frequency band can be achieved. However, actual transmission efficiency would be reduced to 90%. To enhance the effect of the present invention, it is desirable that the transmission circumference distribution according to the present invention be as perfect as possible with the regional distribution of the actual traffic volume.

In indeed, there is an actual one urban Area from a crowded building district and a green belt zone, the this building area surrounds. Even an actual one Suburban area consists of a residential district and fields or one Forest surrounding this residential district. These urban and suburban Areas are similar yourself in the distribution of Tf diagrams. This will be the application of the present invention effectively.

120 FIG. 12 is a diagram showing time slots by the TDMA method, wherein FIG 120 (a) a conventional method and 120 (b) the present invention shows. The conventional method uses time slots 786 (a) . 786 (b) for transmission to portable phones from A, B channels at the same frequency and time slots 787 (a) . 787 (b) for the transmission of the same, as in 120 (a) is shown. In contrast, the 16 SRQAM mode of the present invention uses a timeslot 788 (a) for receiving an A ₁ channel and a time slot 788 (c) to send to an A ₁ channel, as in 120 (b) is shown. A width of the time slot becomes approximately ½. In the case of a 64 SRQAM mode, a time slot will be used 788 (i) for receiving a D ₁ channel and a time slot 788 (l) used to send to a D ₁ channel. A width of the time slot becomes approximately 1/3.

To save electrical power, a transmission from the E ₁ channel is made by using a normal 4 SRQAM time slot 788 (r) while receiving from an E ₁ channel by using a 16 SRQAM time slot 788 (b) , which is a ½ time slot, is performed.

The transmission power is surely suppressed, although communication costs due to a long occupancy time can rise. This will be for a small and lightweight portable phone that comes with a small one Battery or when the battery is nearly empty, be effective.

As described in the above description, it allows the present invention, the distribution of the transmission capacity so too determine that they are with the actual Traffic distribution matches, thereby the transmission capacity significantly increase. Furthermore, the present invention allows base stations or mobile stations, one of two or three transmission capacity free select. When the frequency use efficiency is set lower, the power consumption becomes decreased. If the frequency usage efficiency is set higher, communication costs become saved up. About that addition, the use of a 4 SRQAM mode, which has a smaller capacity, the Simplify circuit and reduce the size and cost of the phone to reduce. As explained in the above embodiments, there is a hallmark of the present invention in that compatibility between all the stations involved is preserved. In this way, the present increases Invention not only the transmission capacity, but allows customers with a wide variety of series from a super-phone to provide up to a high performance telefan.

Embodiment 9

Hereinafter, a ninth embodiment of the present invention will be described with reference to the drawings. The ninth embodiment uses this invention in an OFDM transmission system. 123 is a block diagram of an OFDM transmitter / receiver, and 124 is a diagram showing a principle of OFDM action. An OFDM is one of FDM and has a better efficiency in frequency usage compared to a general FDM, since an FDM sets two adjacent carriers to be shifted by 90 ° from each other. Furthermore, an FDM can tolerate multipath interference such as a ghost, and therefore can be applied to digital music broadcasting or digital television broadcasting.

As in the basic diagram of 124 is shown, an OFDM converts an input signal through a serial-to-parallel converter 791 in data, on a frequency axis 793 are distributed at intervals of 1 / ts, so that secondary channels 794a - 794e be generated. This signal is inverse FFT converted by a modulator 4 which is an inverse FFT 40 has, in a signal on the time axis 799 to a transmission signal 795 to create. This inverse FFT signal is during an effective character portion 796 the time span ts sent. A guard interval 797 that has an amount tg is created between corresponding character portions.

A transmission / reception operation of an HDTV signal according to this ninth embodiment will be described with reference to the block diagram of FIG 123 explains what a hybrid. OFDM CCDM system shows. An input HDTV signal is received from a video encoder 401 in three-level video signals, a video signal in the low frequency band D _1-1, a video signal in the middle-low frequency band D _1-2 and a video signal in the high-middle low frequency band D ₂ , separated and an input section 742 fed.

In a first data stream input 743 For _example, a D _1-1, high code gain signal is ECC encoded, and a D _1-2 signal is ECC encoded with normal code gain. A TDM 743 performs time division multiplexing of D _1-1 and D _1-2 signals to produce a D ₁ signal, which is then a D ₁ serial-to-parallel converter 791d in a modulator 852 is supplied. The D; Signal consists of n parts of parallel data, which are in first inputs of n parts of a C-CDM modulator 4a respectively. 4b be entered.

On the other hand, the signal D ₂ in the high frequency band becomes a second data stream input 744 the entrance section 742 fed into the D ₂ signal in an ECC 744a ECC encoded (error correction code encoded) and then in a trellis encoder 744b Trellis-encoded. Thereafter, the D ₂ signal is sent to a D ₂ serial to parallel converter 791b of the modulator 852 and converted into n pieces of parallel data, which are in second inputs of the n parts of the C-CDM modulator 4a respectively. 4b be entered.

The C-CDM modulators 4a . 4b respectively. 4c generate 16 SRQAM signals based on the D ₁ data of the first data stream input and the D ₂ data of the second data stream input. These n parts of the C-CDM modulator have different carriers from each other. As in 124 shown are the carriers 794a . 794b . 794c on the frequency axis 793 aligned so that two adjacent carriers are 90 ° out of phase with each other. Such C-CDM modulated n parts of the modulated signal become the inverse FFT circuit 40 supplied and from the frequency axis dimension 793 on the timeline dimension 790 displayed. This will be time signals 796a . 796b which have an effective character length ts generated. Between the effective drawing time zones 796a and 796b becomes a guard interval zone 797a created by Tg seconds to lessen multipath interference. 129 is a graph showing a relationship between time axis and signal level. The guard time Tg of the guard interval band 797a is determined by taking into account multipath and signal usage. By setting the guard time Tg longer than the multipath influencing time, eg, a TV noise signal, modulated signals of the inverse FFT circuit become 40 through a parallel-to-serial converter 4e converted into a signal and then from a transmission circuit 5 sent as an RF signal.

Next is the operation of a receiver 43 described. A received signal as a time-based character signal 796e of the 124 is shown is an input circuit 24 from 123 fed. The received signal then becomes a digital signal in a demodulator 852b converted and further into Fourier coefficients in an FFT 40a changed. This will be the signal from the timeline 799 on the frequency axis 793 as in 124 shown shown. That is, the time-based character signal becomes frequency-based carrier 794a . 794b changed. Since these carriers are in quadrature relationship with each other, it is possible to separate correspondingly modulated signals. 125 (b) shows such a demodulated 16 SRQAM signal, which then corresponding C-CDM demodulators 45a . 45b a C-CDM demodulator 45 in which the demodulated 16 SRQAM signal is demodulated into multi-level sub signals D _1, D ₂ . These sub-signals D ₁ and D ₂ are further demodulated by a D ₁ parallel-to-serial converter 852 and a D ₂ parallel-to-serial converter 852b in the original D ₁ and D ₂ signals.

Since the signal transmission system of C-CDM multi-level type, shown in 125 (b) , both D ₁ and D ₂ signals are demodulated under better reception conditions, but only the D ₁ signal will be demodulated under worse reception conditions, eg at low S / N rate. The demodulated D ₁ signal is in an output section 757 demodulated. Since the D _1-1 signal has a higher ECC code gain compared with the D _1-2 signal, an error signal of the D _1-1 signal is reproduced even under a worse receiving condition.

The D _1-1 signal is from a 1-1 video decoder 402c converted into a signal in the low frequency band and output as an LDTV, and the D _1-2 signal is from a 1-2 video decoder 402d converted into a signal in the middle frequency band and output as EDTV.

The D ₂ signal is from a trellis decoder 759b Trellis-decoded and from a second video decoder 402b converted into a signal in the high frequency band and output as a-HDTV signal. Namely, an LDTV signal is output only in the case of the signal in the low frequency band. An EDTV signal of wide NTSC degree is output when the signal in the middle frequency band is added to the signal in the low frequency band, and an HDTV signal is generated by adding signals in the low, middle and high frequency band. As in the previous embodiment, a television signal having an image quality that depends on a reception S / N rate can be received. Thereby, the ninth embodiment realizes a new multi-level signal transmission system by combining an OFDM and a C-CDM which is not obtained by the OFDM alone.

One OFDM is certainly strong against reusable such as television interference signals, since the guard time Tg absorbs an interference signal of the multipath can. Accordingly, OFDM is for digital television transmission applicable to car televisions. Meanwhile, no OFDM signal is received when the S / N rate is lower is a predetermined value, since its signal transmission pattern is not from Is multi-level type.

The However, the present invention can overcome this disadvantage by combining of the OFDM with the C-GDM, whereby thereby a gradual Decrease, depending from the S / N rate in a video signal reception, without through multipath transmission disturbed to become.

If receive a television signal in a compartment of a vehicle not only the reception is disturbed by multipath transmission, but it will also be the S / N rate deteriorated. Therefore, the transmission service area becomes a television broadcasting station can not be extended as expected, if the countermeasure only for reusable transmission is provided.

on the other hand reception of a television signal is at least of the LDTV degree the combination with the multi-level transmission C-CDM ensured even if the S / N rate is significantly reduced. As the size of the image area of a Vehicle TV normally less than 100 inches, becomes a television signal provide adequate picture quality from LDTV grade. This will the coverage area of the LDTV grade of automobile television greatly expanded. If an OFDM is in an entire frequency band of a HDTV signals can be used current semiconductor technologies do not prevent the Circuit scale so far increases.

Now, an OFDM method for transmitting only one D _{1-1 of} a low frequency band television signal will be described below. As in a block diagram in 138 a component D _1-2 in the middle frequency band and a component D ₂ in the high frequency band of an HDTV signal in a C-CDM modulator 4a multiplexed and then through an FDM 40d sent at a frequency band A.

On the other hand, one of a receiver 43 received signal first of all from an FDM 40e Frequency shared and then from a C-CDM demodulator 4b demodulated the present invention. Thereafter, the thus-demodulated C-CDM signal into the medium and high frequency components of the HDTV in the same manner as in 123 reproduced. An operation of a video decoder 402 is identical to that of the embodiments 1, 2 and 3 and will not be explained further.

Meanwhile, the D _1-1 signal, a signal in the low frequency band from the MPEG-1 level of the HDTV, by a serial-to-parallel converter 791 converted into a parallel signal and an OFDM modulator 852c which performs a QPSK or 16 QAM modulation. Hereinafter, the D _1-1 signal from an inverse FFT 40 converted into a time-based signal and at a frequency band B by the FDM 40d Posted.

On the other hand, one of the receiver 43 received signal in the FDM 40e frequency divided and then into a number of frequency based signals in an FFT 40a OFDM modulator 852d changed. Thereafter, frequency-based signals in corresponding demodulators 4a . 4b demodulated and a parallel-to-serial converter 882a in which a D _1-1 signal is demodulated. This will produce a D _1-1 LDTV grade signal from the receiver 43 output.

In this way, only one LDTV signal is OFDM modulated in the multi-level signal transmission. The system of 138 makes it possible to create a complicated OFDM circuit only for an LDTV signal. A bit rate of the LDTV signal is 1/20 of that of an HDTV. Therefore, the circuit scale of the OFDM is reduced to 1/20, resulting in an excellent reduction of the overall switching scale.

An OFDM signal transmission system is strong against multipath transmission and will soon be applied to a mobile station, such as a portable television, a vehicle television or a digital music broadcast receiver that is subject to stronger and variable multipath transmission interference. For such uses, a small image size of less than 10 inches, 4 to 8 inches, is the main direction. It is therefore estimated that the OFDM modulation of a high-definition television signal such as HDTV or EDTV will bring less effect. In other words, the reception of a television signal of the LDTV grade would be sufficient for vehicle television.

in the In contrast, in a fixed station such as a home television, multipath transmission is constant. Therefore, a countermeasure against multipath transmission pretty easy. A lesser effect becomes for such a fixed station brought by OFDM, except in a glitch area. The use of OFDM for Mid and high frequency band components of HDTV are not advantageous in view of the current circuit scale OFDM, who is still big.

Accordingly, the method of the present invention in which OFDM is used only for a television signal in the low frequency band, as in FIG 138 is shown to reduce the circuit scale of the OFDM to less than 1/10 without losing an inherent OFDM effect which is capable of greatly reducing multipath transmission noise of LDTVs upon reception at a mobile station such as a motor vehicle.

Although the OFDM modulation of 138 is performed only for a D _1-1 signal, it is also possible to modulate D _1-1 and D _1-1 by OFDM. In such a case, a C-CDM bi-level signal transmission is used to transmit D _1-1 and D _1-2 . Thereby, a multi-level broadcasting transmission for a vehicle such as a motor vehicle that is strong against multipath transmission is realized. Even in a vehicle, the gradual increase is realized in such a manner that LDTV and SDTV signals are received with image qualities depending on the received signal level or the antenna sensitivity.

The Multi-level signal transmission according to the present Invention is feasible in this way and produces different Effects as described above. When the multi-level signal transmission of the present invention is incorporated into an OFDM furthermore possible are going to create a system that strongly opposes reusable transmission is, and, the data transmission rate according to a change to change the receivable signal level.

The Multi-level signal transmission method The present invention is intended to increase the use of frequencies, mag but not for all the transmission systems be suitable because it causes the energy use in some types of receivers weakened becomes. It is a good idea for use with a satellite communication system for selected participants, extremely advanced Sender and receiver to use, for the best use of the applicable frequencies and the energy are constructed. A signal transmission system for a such specific purpose is not in accordance with the present invention bound.

The present invention is advantageous for use with a satellite or terrestrial television service, which is essentially the same standards been operated for 50 years. During the service period, the Sending standards not changed but improvements will be made from time to time accordingly updated, technological achievements provided. Especially becomes the energy for signal transmission certainly raised at any satellite. Every TV station should provide a compatible service to receive a TV program signal with some kind of receiver to guarantee that from today's general to the most modern in the future is enough. The signal transmission system of the present Invention can provide a compatible television service for both existing NTSC and High definition television systems deliver, and also a future one Make sure extension to get a bulk data transfer adapt.

The rather, the present invention relates to frequency usage the energy use. The signal reception sensitivity of each receiver is different depending configured by a signal state level that is received so that the transmission power a transmitter is not greatly increased must become. Therefore, you can existing satellites that have a small amount of energy to receive and transmit of a signal, preferably with the system of the present Invention can be used. The system is also designed to be same standards according to an increase in the transmission energy in the future and the compatibility between recipients old and new type. Furthermore, the present invention more advantageous for use with the satellite television standards.

The multi-level. Signal transmission method of the present invention is more preferably used for a terrestrial television service; where the energy usage is not critical compared to the satellite television service. The results. are such that the signal attenuation ranges in a coverage area provided to a conventional high definition digital television system The compatibility of a high-definition television receiver or a display device with the existing NTSC system is also obtained. Furthermore, the coverage area is significantly increased so that program providers and sponsors can find more viewers. Although the embodiments of the present invention relate to 16 and 32 QAM methods, other modulation techniques including 64, 128 and 256 QAM are used with equal success. Also, multiple PSK, ASK and FSK techniques are applicable as has been described in the embodiments.

One Combination of TDM with SRQAM of the present invention is above been described. However, the SRQAM of the present invention also with any of FDM, COMA and frequency distribution communication systems be used.

Claims (14)

Signal transmission device ( 1 ) for transmitting a first data stream and a second data stream, comprising: - a first error correction code (ECC) encoder ( 743 ) for ECC-encoding the first data stream to generate an ECC-coded first data stream, - a second error-correcting-code (ECC) -coder ( 744 ) for ECC-encoding the second data stream to generate an ECC-coded second data stream, the first ECC coder ( 743 ) is different from the second ECC encoder ( 744 ), - a modulator ( 4 ) for modulating the ECC-coded first data stream according to a level M m or QAM step M and modulating the ECC-coded second data stream according to a level n or QAM level PSAM to produce modulated signals, where m and n are integers, - an inverse fast Fourier transformer (IFFT; 40 ) for converting the modulated signals into an IFFT converted signal, and - a transmitter ( 5 ) for transmitting the modulated signals, wherein the first data stream contains information representing the value of n. Signal transmission device according to claim 1, where m is equal to or less than 4. Signal transmission device according to claim 1 or claim 2, wherein n is equal to or greater than 4. Signal receiving device ( 43 ) comprising: a fast Fourier transformer (FFT; 40a ) for converting an input signal into an FFT converted signal, the input signal having information of a first data stream and a second data stream, both of which are ECC encoded, the ECC encoded first data stream being in accordance with a level M or QAM PSK is modulated at level m, wherein the ECC encoded second data stream is modulated according to a level n PSK or a level n QAM, where m and n are integers, and wherein the first data stream is information re-presenting the value of n contains, - a demodulator ( 45 ) for demodulating the received signal to produce the ECC encoded first data stream and the ECC encoded second data stream, the ECC encoded second data stream being generated according to the information representing the value of n, a first error correction code (ECC), Decoder ( 758 ) for ECC decoding the ECC encoded first data stream to generate the first data stream, and - a second error correcting code (ECC) decoder ( 759 ) for ECC decoding the ECC encoded second data stream to generate the second data stream, wherein the first ECC decoder ( 758 ) is different from the second ECC decoder ( 759 ). Signal receiving apparatus according to claim 4, wherein m is the same or less than 4. Signal receiving device according to claim 4 or claim 5, where n is equal to or greater than 4 is. Signal transmission system comprising a signal transmission device ( 1 ) according to one of claims 1 to 3 and a signal receiving device ( 43 ) according to one of claims 4 to 6. A signal transmission method for transmitting a first data stream and a second data stream, comprising: - first error correction code (ECC) - encoding the first data stream to generate an ECC-coded first data stream, - second error correction code (ECC) - coding the second data stream, an ECC generating the second encoded data stream, wherein the first ECC encoding is different from the second ECC encoding, modulating the ECC encoded first data stream according to a stage m PSK or a stage m, and modulating the ECC encoded second data stream according to a n-level PSK or n-level QAM to generate modulated signals, where m and n are integers, converting the modulated signal into an IFFT-converted signal, and transmitting the modulated signals, the ers te data stream contains an information representing the value of n. Teleprotection according to claim 8, where m is equal to or less than 4. Teleprotection according to claim 8 or claim 9, wherein n is equal to or greater than 4. Signal reception method comprising: - Convert an input signal to an FFT converted signal, wherein the Input signal information of a first data stream and a second data stream, both of which are ECC encoded, wherein the ECC encoded first data stream is according to a PSK of level m or a QAM of the stage m is modulated, wherein the ECC-coded second data stream according to a PSK of level n or a QAM of level n is modulated, where m and n are integers, and where the first data stream is a Value of n representing Contains information - Demodulate of the received signal to the ECC-coded first data stream and generate the ECC encoded second data stream, wherein the ECC encoded second data stream according to the value of n representing Information is generated - first Error correction code (ECC) decoding the ECC encoded first data stream, to generate the first data stream, and - Second error correction code (ECC) decode of the ECC encoded second data stream to the second data stream where the first ECC decoding is different from the second ECC decode. A signal receiving method according to claim 11, wherein m is the same or less than 4. A signal receiving method according to claim 11 or claim 12, where n is equal to or greater than 4 is. signal transmission and receiving method comprising a signal transmission method according to the claims 8 to 10 and a signal receiving method according to one of claims 11 to 13th